The application relates to a split application of a Chinese national stage patent application with international application number of PCT/IL2017/050616, international application date of 2017, month 06 and 01, and the application name of PCT application of digital printing method, which enters the Chinese national stage after 25 days of 2019 and 01, and application number of 201780046259.1.
The present disclosure claims priority from U.S. patent application Ser. No. 62/343,123 filed 5/30 in 2016 and U.S. patent application Ser. No. 62/343,108 filed 5/30 in 2016, both of which are incorporated herein by reference in their entirety.
Disclosure of Invention
Aspects of the invention relate to a printing process comprising a. Providing an Intermediate Transfer Member (ITM) comprising a silicone-based release layer surface, said surface having sufficient hydrophilicity to meet at least one of (i) a receding contact angle of a distilled water droplet deposited on said silicone-based release layer surface of at most 60 DEG, and (ii) a 10 second Dynamic Contact Angle (DCA) of a distilled water droplet deposited on said silicone-based release layer surface of at most 108 DEG, b. Providing an aqueous treatment formulation comprising i.at least 3 wt% of a quaternary ammonium salt having a solubility in water of at least 5% at 25 ℃, ii.at least 1 wt% of at least one water-soluble polymer having a solubility in water of at least 5% at 25 ℃, and iii. An aqueous carrier liquid, the water comprises at least 65% by weight of the aqueous treatment formulation having the properties of i.a static surface tension at 25 ℃ in the range of 20 dynes/cm and 40 dynes/cm, ii.25 ℃ dynamic viscosity of at least 10cP, and iii.60 ℃ evaporation load of at most 8:1 by weight, c.applying the aqueous treatment formulation to the silicone-based release layer surface of the ITM to form thereon a wet treated layer having a thickness of at most 0.8 μm, d.subjecting the wet treated layer to a drying treatment to form a dried treated film on the silicone-based release layer surface from the wet treated layer, e.depositing droplets of aqueous ink onto the dried treated film to form an ink image on the release layer surface of the silicone-based release layer surface, f.drying the ink image to leave an ink image residue on the silicone-based release layer surface, and g.transferring the ink image residue to the substrate by pressure contact between the ITM and the printing substrate.
Aspects of the invention relate to a printing process comprising a. Providing an Intermediate Transfer Member (ITM) comprising a silicone-based release layer surface, said surface having sufficient hydrophilicity to meet at least one of (i) a receding contact angle of a distilled water droplet deposited on said silicone-based release layer surface of at most 60 DEG, and (ii) a 10 second Dynamic Contact Angle (DCA) of a distilled water droplet deposited on said silicone-based release layer surface of at most 108 DEG, b. Providing an aqueous treatment formulation comprising i.at least 3 wt% of a quaternary ammonium salt having a solubility in water of at least 5% at 25 ℃, ii.at least 1 wt% of at least one water-soluble polymer having a solubility in water of at least 5% at 25 ℃, and iii. An aqueous carrier liquid, the water comprises at least 65% by weight of the aqueous treatment formulation having the properties of i.static surface tension at 25 ℃ in the range of 20 dynes/cm and 40 dynes/cm, ii.25 ℃ dynamic viscosity of at least 10cP, and iii.60 ℃ evaporation load of at most 8:1 by weight, c.applying an aqueous treatment formulation to the silicone-based release layer surface of an ITM to form a wet treated layer thereon, d.subjecting the wet treated layer to a drying treatment to form a drying treated film from the wet treated layer on the silicone-based release layer surface, e.depositing droplets of aqueous ink onto the drying treated film to form an ink image on the release layer surface of the silicone-based release layer surface, f.drying the ink image to leave an ink image residue on the silicone-based release layer surface, and g.transferring the ink image residue to the printing substrate by pressure contact between the ITM and the printing substrate.
Aspects of the invention relate to a printing kit comprising a. An Intermediate Transfer Member (ITM) comprising a silicone-based release layer surface, the surface having sufficient hydrophilicity to satisfy at least one of (i) a receding contact angle of distilled water droplets deposited on the silicone-based release layer surface of at most 60 °, (ii) a 10 second Dynamic Contact Angle (DCA) of distilled water droplets deposited on the silicone-based release layer surface of at most 108 °, and b. An amount of an aqueous treatment formulation comprising i.at least 3 wt% quaternary ammonium salt having a solubility in water of at least 5% at 25 ℃, ii.at least 1 wt% of at least one water-soluble polymer having a solubility in water of at least 5% at 25 ℃, and iii. An aqueous carrier liquid comprising at least 65 wt% of the aqueous treatment formulation, the aqueous treatment formulation having the properties of i.i.at least 3 wt% quaternary ammonium salt having a static surface tension of 20 dynes/40 cm/cm at 25 ℃ and a dynamic load of at least 10.8 cm/cm, and iii.1.v.v.
In some embodiments, the provided aqueous treatment formulation has an evaporation load of at most 6:1, at most 5:1, at most 4:1, at most 3.5:1, or at most 3:1 at 60 ℃, and optionally, at least 2:1, at least 2.2:1, or at least 2.5:1.
In some embodiments, the concentration of the quaternary ammonium salt within the provided aqueous treatment formulation is in the range of 3% to 15%, the concentration of the water soluble polymer is in the range of 2.5% to 10%, or 2.5% to 8%, the evaporation load at 60 ℃ is in the range of 2.5:1 to 4:1, and the viscosity is at least 12cP, and optionally, at least 14cP or at least 16cP.
In some embodiments, the aqueous treatment formulation provided therein has a total surfactant concentration in the range of at least 6%, at least 7%, at least 8%, at least 9%, or at least 10%, and optionally, from 6% to 40%, from 6% to 30%, from 6% to 20%, from 7% to 30%, from 7% to 20%, from 7% to 15%, from 8% to 25%, from 8% to 20%, from 8% to 15%, or from 8% to 13%.
In some embodiments, the total concentration of organic solvents within the provided aqueous treatment formulation is at most 3wt%, at most 2wt%, at most 1wt%, or at most 0.5 wt%, or wherein the formulation is free of organic solvents.
In some embodiments, the total concentration of liquid hygroscopicity in the aqueous treatment formulation provided is at most 1.5 wt%, at most 1 wt%, at most 0.5 wt%, at most 0.3 wt%, or at most 0.1 wt%, or wherein the aqueous treatment formulation is free of liquid hygroscopicity.
In some embodiments, the quaternary ammonium salt of the provided aqueous treatment formulation is an organic quaternary ammonium salt.
In some embodiments, the first carbon chain of the organic quaternary ammonium salt has at least 6 carbon atoms, and optionally, a length in the range of 6 to 20, 6 to 18, 8 to 20, or 8 to 18 carbon atoms.
In some embodiments, wherein the second carbon chain of the organic quaternary ammonium salt has a length of up to 3 carbon atoms or up to 2 carbon atoms.
In some embodiments, wherein the third carbon chain of the organic quaternary ammonium salt has a length of up to 3 carbon atoms, up to 2 carbon atoms, or 1 carbon atom.
In some embodiments, the organic quaternary ammonium salt is a cationic organic quaternary ammonium salt optionally having sulfate or phosphate anions.
In some embodiments, the silicone-based release layer surface has sufficient hydrophilicity to satisfy at least one of a receding contact angle of a distilled water droplet deposited on the silicone-based release layer surface of at most 60 °.
In some embodiments, the silicone-based release layer surface is sufficiently hydrophilic such that a 10 second Dynamic Contact Angle (DCA) of a distilled water droplet deposited on the silicone-based release layer surface is at most 108 °.
In some embodiments, an ITM is provided comprising a support layer and a release layer having a surface of the silicone-based release layer and a second surface opposite the surface of the silicone-based release layer, and (ii) attached to the support layer, the release layer formed from an addition cured silicone material, and the release layer having a thickness of at most 500 micrometers (μm).
In some embodiments, the release layer of the provided ITM consists essentially of, or contains at least 95 wt% addition cured silicone.
In some embodiments, functional groups within the silicone-based release layer surface of the provided ITM comprise up to 3 wt% of the addition-cured silicone material.
In some embodiments, a polyether glycol functionalized polydimethyl silicone is impregnated in the addition cured silicone material of the provided ITM.
In some embodiments, the provided release layer of the ITM is adapted such that the polar groups of the ink receiving surface have an orientation away from or opposite the second surface.
In some embodiments, the surface hydrophobicity of the silicone-based release layer surface of the provided ITM is less than the bulk hydrophobicity of the cured silicone material in the release layer, the surface hydrophobicity being characterized by the receding contact angle of distilled water droplets on the ink receiving surface, the bulk hydrophobicity being characterized by the receding contact angle of distilled water droplets disposed on the inner surface formed by exposing regions of the cured silicone material in the release layer to form exposed regions.
In some embodiments, the aqueous treatment formulation is applied to the silicone-based release layer surface such that the thickness of the wet treatment layer is at most 0.6 μm, at most 0.5 μm, or at most 0.4 μm.
In some embodiments, the wet treatment layer is formed and/or thinned by pushing a circular surface towards the ITM, or vice versa, wherein i. the circular surface has a radius of curvature of at most 2mm, or at most 1.5mm, or at most 1.25mm, or at most 1mm, and/or ii. the pushing is performed in a cross-printing direction with a force density of at least 250g/cm, or at least 350g/cm, or at least 400gm/cm and/or at most 1kg/cm, or at most 750g/cm, or at most 600 g/cm, and/or iii. the pushing is performed by applying a pressure between the ITM, the pressure having a magnitude of at least 0.1 bar, or at least 0.25 bar, or at least 0.35 bar, or at least 0.5 bar, and optionally at most 2 bar, or at most 1.5 bar.
In some embodiments, the wet treatment layer is formed and/or thinned by a stationary applicator and/or a rounded surface that directly or indirectly applies a force to the running ITM to (i) deform the ITM to cause dishing therein, and (ii) establish a velocity gradient of the flowing aqueous treatment formulation that is formed in the normal direction of the ITM and in the interstitial region between the ITM and the stationary applicator.
In some embodiments, the magnitude of the velocity gradient is at least 106sec-1, or at least 2x 106sec-1.
In some embodiments, the aqueous treatment formulation is applied to at least a portion or portions of the ITM that run at a speed of at least 1 meter/second, or at least 1.5 meters/second, or at least 2 meters/second, to form a wet treatment layer thereon.
In some embodiments, the forming of the wet treatment layer or the thinning thereof comprises forcing the aqueous treatment formulation to flow, thereby causing a velocity gradient to be established in the ITM's normal direction, the velocity gradient having a magnitude of at least 106sec-1 or at least 2x 106sec-1.
In some embodiments, the release surface of the ITM has a shore a hardness of at most 50, or at most 45, or at most 40, or at most 35, or at most 30, or at most 25, or at most 20, or at most 15.
In some embodiments, the drying treatment of the wet treated layer is sufficiently rapid, thereby allowing the viscosity of the aqueous treatment formulation to rapidly increase sufficiently to inhibit surface tension driven beading, thereby allowing the dried treated film to have a smooth upper surface.
In some embodiments, the smooth upper surface of the dried treated film is characterized by an average roughness Ra of at most 12 nanometers, or at most 10 nanometers, or at most 9 nanometers, or at most 8 nanometers, or at most 7 nanometers, or at most 5 nanometers.
In some embodiments, the drying of the treatment solution is performed fast enough to prevent beading and leave a continuous hydrophilic and cohesive polymer treatment film having a thickness of at most 200nm, or at most 150nm, or at most 120nm, or at most 100nm, or at most 80nm, or at most 70nm, or at most 60nm, or at most 50nm, or at most 40nm, or at most 30 nm.
In some embodiments, the thickness of the dried treated film that deposits the aqueous ink droplets is at most 200nm, or at most 120nm, or at most 100nm, or at most 80nm.
In some embodiments, the thickness of the dried treated film of deposited aqueous ink droplets is at least 15nm, or at least 20nm, or at least 30nm.
In some embodiments, the drying treatment film is continuous across the rectangle of the release surface of the ITM, wherein the rectangle has a width of at least 10cm and a length of at least 10 m.
In some embodiments, the dried film comprises at least 50%, or at least 75%, or at least 90%, or at least 95%, or at least 99%, or 100% of the rectangular area, and the thickness of the dried film does not deviate by more than 50%, or not more than 40%, or not more than 30% from the average thickness value within the rectangle
In some embodiments, the dynamic viscosity of the wet treated layer increases by at least a factor of 1000 over a period of up to 250 milliseconds during the drying process of the wet treated layer.
In some embodiments, the liquid content of the drying treatment film is at most 10 wt%, or at most 7.5 wt%, or at most 5 wt%, or at most 2.5 wt%, or at most 1.5 wt%, or at most 1 wt%.
In some embodiments, droplets of aqueous ink are deposited onto the drying treatment film by inkjet.
In some embodiments, the ink image residue is transferred to the print substrate along with the non-printed areas of the dry processing film.
In some embodiments, the thickness of the dried treatment film is up to 120nm.
In some embodiments, the drying treatment film has sufficient cohesiveness such that during transfer of the ink image residue, in both the printed and non-printed areas, the drying treatment film is completely separated from the ITM and transferred to the print substrate with the dried ink image.
In some embodiments, the transfer of the ink image residues is performed at a transfer temperature of at most 100 ℃ or at most 90 ℃.
In some embodiments, the solids of the aqueous ink (e.g., nanopigments and/or resins) migrate into the bulk of the drying treatment film to interact with (e.g., bind to) the quaternary ammonium salt residing within the drying treatment film (e.g., so as to facilitate droplet spreading).
In some embodiments, the solids of the aqueous ink migrate into the bulk of the drying treatment film to interact with the quaternary ammonium salt residing within the drying treatment film in order to facilitate droplet spreading.
In some embodiments, the method is performed such that i.a set of ink dots IDS is formed where the ink substrate resides; a plurality of droplets DP of said aqueous ink droplets deposited onto said ITM resident drying treatment film form a set of ink droplets IDS of an ink substrate resident ink dot such that there is a correspondence between a. Each given droplet of said plurality of droplets DP and b. Each given substrate resident ink droplet of said set of ink droplets such that said given droplet produces and/or evolves into said given substrate resident ink dot, iii. During deposition, each droplet of said plurality of droplets collides with said drying treatment film on said ITM, the kinetic energy of said impinging droplet deforms said droplet, iv. The maximum radius of impact of each said deformed droplet on the surface of said ITM has a maximum radius of impact value R maximum impact, v. After impact, the physical chemistry forces cause said deformed droplet such that each droplet of the set of ink droplets IDS has a dry point radius R dry spot on substrate, vi. The ratio of said maximum radius of impact of each droplet of said plurality of droplets to said substrate resident droplet is at least between said radius of impact value R35 and R35.
In some embodiments, the method is performed such that i.a plurality of droplets DP of the droplets deposited onto the ITM resident drying treatment film produce a set of ink spots IDS of substrate resident ink spots (i.e. fixedly adhered to a top substrate surface), each droplet of the plurality of droplets DP corresponding to a different respective substrate resident ink spot of the set of ink spots IDS ii. Each droplet of the plurality of droplets DP is deposited onto the substrate according to a jetting parameter iii. The jetting parameter together with the physicochemical properties of the droplet of the plurality of droplets DP together define an inkjet paper spot radius R direct spraying onto ink-jet paper, which is the radius of the ink spot obtained by jetting the droplet directly onto inkjet paper instead of onto the drying treatment film, and iv. The ratio between the dry spot radius R dry spot on substrate of the ink spot of (a) set of ink spots IDS and the inkjet paper spot radius R direct spraying onto ink-jet paper , theory of is at least 1.1.
In some embodiments, the cardinality of the set of ink dots is at least 5, or at least 10, or at least 20, or at least 50, or at least 100, each ink dot of the set of ink dots being different on the substrate.
In some embodiments, the ink dots of the ink dot set are contained within a square geometric projection projected onto the print substrate, each ink dot of the ink dot set being fixedly adhered to the surface of the print substrate, all of the ink dots within the square geometric projection being counted as individual members of the ink dot set IDS.
In some embodiments, the method is performed such that i.a collection of ink dots IDS forming ink substrate-resident ink dots, ii.a collection of ink dots each having a base of at least 5, or at least 10, or at least 20, or at least 50, or at least 100, different on the substrate, iii.the collection of ink dots each comprising a substantially convex shape projected onto the print substrate within a square geometric projection, each of the collection of ink dots being fixedly adhered to a surface of the print substrate, all of the ink dots within the square geometric projection being counted as individual members of the collection of ink dots IDS, iv.each of the ink dots comprising at least one colorant dispersed in an organic polymer resin, each of the dots having an average thickness of less than 2,000nm and a diameter of 5 micrometers to 300 micrometers, v.each of the collection of ink dots having a substantially convex shape, wherein the deviation from DC to DC is defined by the average contour of no more than 0.022.03.025, and the deviation from DC to no more than 0.025, no more than 0.014.03.025, and the average surface area of no more than 0.025, no more than 0.08, and no more than 0.025, no more than 0.0.08, no more than 0.08, and no more than 0.08, no more than the area of the area is calculated by the area.
In some embodiments, the aqueous treatment formulation is applied to at least a portion or portions of the ITM that run at a speed of at least 1 meter/second, or at least 1.5 meters/second, or at least 2 meters/second, to form a wet treatment layer thereon.
In some embodiments, the method is performed such that the water-soluble polymer concentration of the water-soluble polymer within the aqueous treatment formulation is at most 10 wt%, or at most 8 wt%, or at most 6 wt%, or at most 5 wt%.
An aqueous treatment formulation for use with an intermediate transfer member of a printing system, the aqueous treatment formulation comprising (a) a first surfactant composition comprising a first surfactant comprising a quaternary ammonium salt having a solubility in water of at least 5% at 25 ℃, (b) at least 1% by weight of a water soluble polymer having a solubility in water of at least 5% at 25 ℃, and (C) an aqueous carrier liquid, the water comprising at least 65% by weight of the treatment formulation, wherein the concentration of the quaternary ammonium salt within the aqueous treatment formulation is at least 3% by weight, and wherein the treatment formulation has (i) a static surface tension at 25 ℃ in the range of 20 dynes/cm and 40 dynes/cm, (ii) an evaporation load at 60 ℃ of at most 8:1 by weight and (iii) a viscosity at 25 ℃ in the range of 10cP to 100 cP.
In some embodiments, the solubility of the quaternary ammonium salt is at least 7%, at least 10%, at least 15%, or at least 20%, optionally, up to 50%, up to 40%, or up to 35%, or further optionally, in the range of 5% to 40%, 5% to 30%, 5% to 25%, 7% to 35%, 10% to 35%, 12% to 35%, or 15% to 35%.
In some embodiments, the concentration of the quaternary ammonium salt within the aqueous treatment formulation is at least 4%, at least 5%, at least 6%, or at least 7%, optionally, at most 30%, at most 25%, or at most 20%, or further optionally, in the range of 2% to 30%, 3% to 30%, 4% to 20%, 5% to 25%, 6% to 20%, or 7% to 20%.
In some embodiments, the concentration of the water-soluble polymer within the aqueous treatment formulation is in the range of at least 1.5 wt%, or at least 2 wt%, at least 2.5 wt%, at least 3 wt%, or at least 3.5 wt%, optionally, at most 10 wt%, or at most 9 wt%, or at most 8 wt%, or at most 7 wt%, or at most 6 wt%, or further optionally, 1.5 wt% to 20 wt%, or 2 wt% to 10 wt%, 2 wt% to 8 wt%, 2 wt% to 7 wt%, 2.5 wt% to 10 wt%, 2.5 wt% to 8 wt%, 2.5 wt% to 7 wt%, 2.5 wt% to 6 wt%, 3 wt% to 8 wt%, 3 wt% to 6 wt%, 3.5 wt% to 10 wt%, 3.5 wt% to 8 wt%, 3.5 wt% to 7 wt%, 3.5 wt% to 6 wt%, or 4 wt% to 6 wt%.
In some embodiments, the solubility of the water-soluble polymer in water is at least 7%, at least 10%, at least 12%, or at least 15%.
In some embodiments, wherein the water-soluble polymer is selected from the group consisting of polyvinyl alcohol, water-soluble cellulose, polyvinylpyrrolidone (PVP), polyethylene oxide, polyethylene imine, and water-soluble acrylate.
In some embodiments, wherein the 60 ℃ evaporation load is at most 6:1, or at most 5:1, at most 4:1, at most 3.5:1, or at most 3:1, and optionally, at least 2:1, at least 2.2:1, or at least 2.5:1.
In some embodiments, a second surfactant selected for reducing the static surface tension of the aqueous treatment formulation is also included, wherein the second surfactant is optionally a silicone polyether, the second surfactant optionally having a concentration within the formulation in the range of at least 1 wt%, at least 1.5 wt%, at least 2 wt%, at least 2.5 wt%, or at least 3 wt%, optionally up to 15 wt%, up to 12 wt%, up to 10 wt%, up to 8 wt%, or up to 7 wt%, or further optionally, 1.5 wt% to 13 wt%, 1.5 wt% to 10 wt%, 2 wt% to 13 wt%, 2.5 wt% to 10 wt%, or 3 wt% to 10 wt%.
In some embodiments, the treatment formulation further comprises a water absorbing agent disposed within the carrier liquid at least in the range of 25 ℃ to 60 ℃, whereby the water absorbing agent acts as a water absorbent when the aqueous treatment solution is evaporated to form a solid film.
In some embodiments, a water absorbing agent disposed within the carrier liquid, the water absorbing agent being solid in at least the range of 25 ℃ to 60 ℃ in a pure state, whereby the water absorbing agent acts as a water absorbent when the aqueous treatment solution is evaporated to form a solid film.
In some embodiments, the water-absorbing agent has a concentration of 1% to 25%, 1% to 15%, 1% to 10%, 2.5% to 20%, 2.5% to 12%, 3% to 15%, 3% to 12%, 3% to 10%, or 3.5% to 12%.
In some embodiments, the concentration of the quaternary ammonium salt is in the range of 3% to 15%, the concentration of the water soluble polymer is in the range of 2.5% to 10%, or 2.5% to 8%, or 2.5% to 7%, or 2.5% to 6%, the 60 ℃ evaporation load is in the range of 2.5:1 to 4:1, and the viscosity is at least 12cP, and optionally, at least 14cP or at least 16cP.
In some embodiments, the static surface tension is in the range of 25 dynes/cm to 36 dynes/cm.
In some embodiments, the water-absorbing agent has a concentration of 2.5% to 10%.
In some embodiments, the aqueous treatment formulation has a total surfactant concentration in the range of at least 6%, at least 7%, at least 8%, at least 9%, or at least 10%, and optionally, from 6% to 40%, from 6% to 30%, from 6% to 20%, from 7% to 30%, from 7% to 20%, from 7% to 15%, from 8% to 25%, from 8% to 20%, from 8% to 15%, or from 8% to 13%.
In some embodiments, all components of the aqueous treatment formulation are completely dissolved.
In some embodiments, the total concentration of organic solvents within the aqueous treatment formulation is at most 3 wt%, at most 2 wt%, at most 1 wt%, or at most 0.5 wt%, or wherein the formulation is free of organic solvents.
In some embodiments, the total concentration of liquid hygroscopicity agent within the aqueous treatment formulation is at most 1.5 wt%, at most 1 wt%, at most 0.5 wt%, at most 0.3 wt%, or at most 0.1 wt%, or wherein the aqueous treatment formulation is free of liquid hygroscopicity agent.
In some embodiments, the quaternary ammonium salt is an organic quaternary ammonium salt.
In some embodiments, the first carbon chain of the organic quaternary ammonium salt has at least 6 carbon atoms, and optionally, a length in the range of 6 to 20, 6 to 18, 8 to 20, or 8 to 18 carbon atoms.
In some embodiments, the second carbon chain of the organic quaternary ammonium salt has a length of up to 3 carbon atoms or up to 2 carbon atoms.
In some embodiments, the third carbon chain of the organic quaternary ammonium salt has a length of up to 3 carbon atoms, up to 2 carbon atoms, or1 carbon atom.
In some embodiments, the organic quaternary ammonium salt is a cationic organic quaternary ammonium salt optionally having sulfate or phosphate anions.
In some embodiments, the polyethylenimine comprises at most 0.8 wt%, 0.6 wt%, 0.4 wt%, or 0.3 wt%, or 0.2 wt%, or 0.1 wt% of the formulation, or wherein the polyethylenimine comprises at most 30%, at most 20%, at most 15%, at most 10%, or at most 5% of the water-soluble polymer.
In some embodiments, the viscosity is at least 12cP, at least 14cP, or at least 16cP, optionally, at most 90cP, at most 80cP, at most 70cP, at most 60cP, at most 55cP, or at most 50cP, and further optionally, in the range of 10cP to 80cP, 12cP to 60cP, 12cP to 55cP, or 14cP to 60 cP.
In some embodiments, the water-soluble polymer concentration of the water-soluble polymer in the aqueous treatment formulation is at most 10 wt%, or at most 8 wt%, or at most 6 wt%, or at most 5 wt%.
In some embodiments, the provided ITM comprises (a) a support layer; and (b) a release layer having an ink receiving surface for receiving an ink image, and a second surface opposite the ink receiving surface, the second surface being adhered to the support layer, the release layer being formed of an addition cured silicone material, the release layer having a thickness of at most 500 micrometers (μm), ITM satisfying at least one of the structural properties of (1) the total surface energy of the ink receiving surface being at least 2mN/m higher than the total surface energy of a modified ink receiving surface generated by subjecting the ink receiving surface of the respective release layer to a standard aging procedure, at least 3mN/m, at least 4mN/m, at least 5mN/m, at least 6mN/m, at least 8mN/m, or at least 10mN/m, the total surface energy of the ink receiving surface being at least 4mN/m, at least 6mN/m, at least 8mN/m, or at least 10mN/m higher than the total surface energy of a hydrophobic ink receiving surface of the respective release layer prepared by standard air curing of a silicone precursor of the cured silicone material, (2) the total surface energy of the release layer being at least 4mN/m, at least 6mN/m, at least 8mN/m, at least 10mN/m, at least 14 mg, at least 12 mg, at least 10 mg/m, at least 12 mg, at least 10 mg, at least 12 mg, at least the surface of the respective release layer prepared by the standard air curing of the respective release layer, and at least the respective release layer being at least one of the surface, and (b) having a water-resistant layer, and a water-resistant layer, which is opposite to the ink-receiving layer At least 16 °, at least 18 °, or at least 20 °; (4) a receding contact angle of a distilled water droplet on the ink receiving surface that is at least 5 °, at least 6 °, at least 7 °, or at least 8 °, less than a receding contact angle of a distilled water droplet on an aging surface generated by subjecting the ink receiving surface to a standard aging procedure, (5) a surface hydrophobicity of the ink receiving surface that is less than a bulk hydrophobicity of the cured silicone material within the exfoliation layer, the surface hydrophobicity being characterized by a receding contact angle of a distilled water droplet on the ink receiving surface that is characterized by a receding contact angle of a distilled water droplet disposed on an inner surface formed by exposing a region of the cured silicone material within the exfoliation layer to form an exposed region, wherein the receding contact angle measured on the ink receiving surface is at least 7 °, at least 8 °, at least 10 °, at least 12 °, at least 14 °, at least 16 °, at least 18 °, or at least 20 °, at most 60 °, at most 58 °, at most 52 °, at most 40 °, at most 50 °, at most 40 °, at most 44 °, at most 50 °, at most 44 °, at most 40 °, or at most 6) a receding contact angle of a distilled water droplet on the ink receiving surface is provided on the inner surface formed by exposing the region of the cured silicone material to form an exposed region.
In some embodiments, the addition cured silicone material consists essentially of, or contains at least 95 weight percent of, the addition cured silicone.
In some embodiments, the functional groups comprise at most 5wt%, at most 3wt%, at most 2 wt%, or at most 1 wt% of the addition cured silicone material, or wherein the addition cured silicone material is substantially free of the functional groups.
In some embodiments, a polyether glycol functionalized polydimethylsiloxane is impregnated in the addition cured silicone material.
In some embodiments, the polyether glycol functionalized siloxane is impregnated in the addition cured silicone material, but does not form part of the covalent structure of the addition cured silicone material.
An Intermediate Transfer Member (ITM) for use with a printing system (e.g., this may be an ITM of the 'provided ITM'), the ITM comprising (a) a support layer, and (b) a release layer having an ink receiving surface for receiving an ink image, and a second surface opposite the ink receiving surface, the second surface being attached to the support layer, the release layer being formed of an addition cured silicone material, the release layer having a thickness of at most 500 micrometers (μm), the ink receiving surface being adapted to meet at least one of the following structural properties, (i) a receding contact angle of a distilled water droplet on the ink receiving surface of at most 60 °, (ii) a dynamic contact angle of at most 108 ° for a distilled water droplet deposited on the ink receiving surface, and wherein the release layer has at least one of the following structural properties, (1) the addition cured silicone material consisting essentially of an addition cured silicone material, or an addition cured silicone containing at least 95% by weight of the addition cured silicone material, (2) a weight curable silicone material of at most 3%.
In some embodiments, the receding contact angle is at most 58 °, at most 56 °, at most 54 °, at most 52 °, at most 50 °, at most 48 °, at most 46 °, at most 44 °, at most 42 °, at most 40 °, at most 38 °, or at most 37 °.
In some embodiments, in the provided ITM (i.e., printing method), the functional groups constitute at most 2 wt%, at most 1 wt%, at most 0.5 wt%, at most 0.2 wt%, or at most 0.1 wt% of the addition cured silicone material or the release layer surface, or the addition cured silicone material (or the release layer surface) is substantially free of such functional groups. In some embodiments, a polyether glycol functionalized polydimethylsiloxane is impregnated in the addition cured silicone material.
In some embodiments, the provided ITM (i.e., printing method) has the feature that polyether diol functionalized siloxanes are impregnated in the addition cured silicone material, but do not form part of the covalent structure of the addition cured silicone material.
In some embodiments, the ITM (i.e., printing method) provided has the feature that the thickness of the release layer is at most 500 μm, at most 100 μm, at most 50 μm, at most 25 μm, or at most 15 μm.
In some embodiments, the ITM (i.e., printing method) provided has the feature that the thickness of the release layer is in the range of 1 μm to 100 μm, 5 μm to 100 μm, 8 μm to 100 μm, 10 μm to 100 μm, or 10 μm to 80 μm.
In some embodiments, the ITM (i.e., printing method) provided has the feature that the support layer has a thickness in the range of about 50 micrometers (μ) to 1000 μ,100 μ to 800 μ, or 100 μ to 500 μ.
In some embodiments, the ITM (i.e., printing method) is provided having the feature that the total surface of the ink receiving surface can be at least 2J/m2, at least 3J/m2, at least 4J/m2, at least 5J/m2, at least 6J/m2, at least 8J/m2, or at least 10J/m2 higher than the total surface of the modified ink receiving surface generated by subjecting the ink receiving surface of the corresponding release layer to standard aging procedures.
In some embodiments, the provided ITM (i.e., printing method) has the feature that the total surface energy of the ink receiving surface is at least 4J/m2, at least 6J/m2, at least 8J/m2, at least 10J/m2, at least 12J/m2, at least 14J/m2, or at least 16J/m2 greater than the total surface energy of the hydrophobic ink receiving surface of a corresponding release layer prepared by standard air curing of the silicone precursor of the cured silicone material.
In some embodiments, the provided ITM (i.e., printing method) has the feature wherein the receding contact angle of the distilled water droplet on the ink-receiving surface is at least 7 °, at least 8 °, at least 10 °, at least 12 °, at least 15 °, at least 18 °, or at least 20 ° lower than the receding contact angle of the distilled water droplet on the ink-receiving surface of a corresponding release layer prepared by standard air curing of the cured silicone precursor of the silicone material.
In some embodiments, the receding contact angle of the distilled water drop on the ink-receiving surface is at least 5 °, at least 6 °, at least 7 °, or at least 8 ° lower than the receding contact angle of the distilled water drop on an aging surface generated by subjecting the ink-receiving surface to a standard aging procedure.
In some embodiments, the surface hydrophobicity of the ink receiving surface is less than the bulk hydrophobicity of the cured silicone material in the release layer, the surface hydrophobicity characterized by the receding contact angle of distilled water droplets on the ink receiving surface, the bulk hydrophobicity characterized by the receding contact angle of distilled water droplets disposed on an inner surface formed by exposing regions of the cured silicone material in the release layer to form exposed regions.
In some embodiments, the provided ITM (i.e., printing method) has the feature that the receding contact angle measured on the ink receiving surface is at least 7 °, at least 8 °, at least 10 °, at least 12 °, at least 14 °, at least 16 °, at least 18 °, or at least 20 ° lower than the receding contact angle measured on the exposed region.
In some embodiments, the receding contact angle of the distilled water drop on the ink-receiving surface is at least 25 °, at least 28 °, at least 30 °, at least 32 °, at least 34 °, or at least 36 °, and further optionally, in the range of 25 ° to 60 °, 28 ° to 60 °, 30 ° to 55 °, 30 ° to 50 °, 32 ° to 60 °, 32 ° to 55 °, 32 ° to 44 °, 35 ° to 60 °, 35 ° to 55 °, 36 ° to 44 °, or 38 ° to 50 °.
In some embodiments, the release layer is adapted such that the polar groups of the ink receiving surface have an orientation away from or opposite the second surface.
In some embodiments, the release layer is adapted such that when the ITM is in the operational mode, the ink receiving surface is exposed to an ambient environment, the polar groups of the ink receiving surface having an orientation towards or facing the ambient environment.
In some embodiments, the provided ITM (i.e., printing method) has the feature that the ITM forms a component in a digital printing system.
In some embodiments, the provided ITM (i.e., printing method) has the feature that the support layer comprises an elastomeric compliant layer attached to the second surface of the release layer, the elastomeric compliant layer being adapted to closely follow the surface profile of a printing substrate upon which the ink image is imprinted.
In some embodiments, the provided ITM (i.e., printing method) has the feature that the support layer comprises a reinforcing layer attached to the compliant layer.
In some embodiments, the provided ITM (i.e., printing method) has the feature that the release layer contains a total amount of functional groups within its silicone polymer matrix of at most 3wt%, at most 2wt%, at most 1 wt%, at most 0.5 wt%, at most 0.2 wt%, or substantially 0 wt%.
In some embodiments, the provided ITM (i.e., printing method) has the feature that the release layer contains a total amount of functional groups within its silicone polymer matrix of at most 3 wt%, at most 2 wt%, at most 1 wt%, at most 0.5 wt%, at most 0.2 wt%, or substantially 0 wt% selected from the group consisting of c= O, S = O, O-H and COO.
In some embodiments, the ITM (i.e., printing method) is provided having the feature that the release layer contains a total amount of up to 3 wt%, up to 2 wt%, up to 1 wt%, up to 0.5 wt%, up to 0.2 wt%, or substantially 0 wt% of functional groups selected from the group consisting of silane, alkoxy, amido, and amido-alkoxy moieties within its silicone polymer matrix.
In some embodiments, the ITM (i.e., printing method) is provided having the feature that the release layer contains a total amount of up to 3 wt%, up to 2 wt%, up to 1 wt%, up to 0.5 wt%, up to 0.2 wt%, or substantially 0 wt% of functional groups selected from the group consisting of amines, ammonium, aldehydes, SO2、SO3、SO4、PO3、PO4, and C-O-C within its silicone polymer matrix.
In some embodiments, the provided ITM (i.e., printing method) has the feature that the addition cured silicone material has a structure composed of vinyl functional silicone.
In some embodiments, the provided ITM (i.e., printing method) has the feature that the addition cured silicone material comprises polar groups of the "MQ" type.
In some embodiments, the provided ITM (i.e., printing method) has the feature that the total surface energy of the ink receiving surface is assessed using an Owens-Wendt surface energy model.
In some embodiments, the provided ITM (i.e., printing method) has the characteristic that the 10 second DCA is at most 108 °, at most 106 °, at most 103 °, at most 100 °, at most 96 °, at most 92 °, or at most 88 °, optionally at least 60 °, at least 65 °, at least 70 °, at least 75 °, at least 78 °, at least 80 °, at least 82 °, at least 84 °, or at least 86 °, and further optionally in the range of 60 ° to 108 °, 65 ° to 105 °, 70 ° to 100 °, 70 ° to 96 °, 70 ° to 92 °, 75 ° to 105 °, 75 ° to 100 °, 80 ° to 105 °, 80 ° to 100 °, 85 ° to 105 °, or 85 ° to 100 °.
In some embodiments, the provided ITM (i.e., printing method) has the feature that the ink receiving surface is adapted such that for the distilled water droplets deposited on the ink receiving surface, the difference between the 70 second Dynamic Contact Angle (DCA) and the 10 second DCA is at least 7 °, at least 8 °, at least 10 °, or at least 12 °, optionally at most 25 °, at most 22 °, at most 20 °, at most 18 °, or at most 17 °, and further optionally in the range of 6 ° to 25 °,6 ° to 22 °,6 ° to 20 °,6 ° to 18 °,6 ° to 17 °,7 ° to 25 °,7 ° to 20 °,7 ° to 17 °,8 ° to 25 °,8 ° to 22 °, 18 ° to 20 °,8 ° to 18 °,8 ° to 17 °,10 ° to 25 °,10 ° to 22 °,10 ° to 20 °,10 ° to 18 °, or 10 ° to 17 °.
In some embodiments, the ink receiving surface is adapted for the distilled water droplets deposited on the ink receiving surface, the 70 second DCA is in a range of at most 92 °, at most 90 °, at most 88 °, at most 85 °, at most 82 °, at most 80 °, at most 78 °, at most 76 °, at most 74 °, or at most 72 °, optionally at least 55 °, at least 60 °, at least 65 °, or at least 68 °, and further optionally 55 ° to 92 °, 55 ° to 90 °, 55 ° to 85 °, 55 ° to 80 °, 65 ° to 92 °, 65 ° to 90 °, 65 ° to 85 °, 65 ° to 80 °, 68 ° to 85 °, 68 ° to 80 °, 70 ° to 92 °, 70 ° to 90 °, to 70 ° to 85 °, or 70 ° to 80 °.
According to various aspects of the present invention there is provided a printing system comprising a. An Intermediate Transfer Member (ITM) comprising a flexible endless belt mounted on a plurality of guide rollers, b. An image forming station configured to form an ink image on a surface of the ITM, a first guide roller and a second guide roller being arranged upstream and downstream of the image forming station to define an upper run and a lower run through the image forming station, b. An embossing station through which the lower run of the ITM passes, the embossing station being arranged downstream of the image forming station and configured to transfer the ink image from the ITM surface to a substrate, and d. A treatment station arranged downstream of the embossing station and upstream of the image forming station for forming a uniform thin layer of liquid treatment formulation on the ITM surface on its lower run, the treatment station comprising i. A coater for coating the ITM with the liquid treatment formulation and ii. A tip thickness regulator for removing the liquid only to leave the desired thin layer thickness regulator of the desired thin layer of the liquid treatment formulation facing the rounded assembly surface.
In some embodiments, the rounded tip is the tip of a spatula.
In some embodiments, the doctor blade is oriented normal to the ITM surface.
In some embodiments, the rounded tip is pushed toward the ITM surface and/or vice versa.
In some embodiments, the rounded tip is pushed toward the ITM surface and/or vice versa by a backing roll having a soft outer surface.
In some embodiments, (i) the backing roller is disposed inside the closed loop of the endless belt and positioned opposite the blades and/or (ii) the backing roller and rounded tip are disposed on opposite sides of the lower run of the ITM.
In some embodiments, the outer surface of the backing roll has one or more of (i) elasticity, (ii) zero memory, (iii) an outer surface that retains its softness over a range of temperatures, and (iv) is constructed from polyurethane.
In some embodiments, the difference between the maximum and minimum of the temperature ranges is at least 10 ℃, or at least 20 ℃, or at least 50 ℃ and/or the average of the temperature ranges is between 50 ℃ and 120 ℃.
In some embodiments, the backing roll has a compressible surface that is compressed when the rounded tips are pushed toward the ITM surface and/or vice versa, thereby causing the rounded tips to penetrate into the compressible surface of the backing roll along with the ITM at a predetermined penetration depth.
In some embodiments, the depth of penetration is at least 1mm, or at least 2mm and/or at most 5mm, or at most 4mm, or at most 3mm in size.
In some embodiments, the doctor blade extends substantially across the width of the ITM.
In some embodiments, the length of the doctor blade (measured in the cross-printing direction) is at least 10cm or at least 30cm, and optionally, at least 50cm, at least 70cm, or at least 100cm, and optionally, at most 250cm, at most 200cm, or at most 150cm.
In some embodiments, the length of the doctor blade (measured in the cross-printing direction) is in the range of 50 to 250cm, 70 to 250cm, 100 to 250cm, 70 to 200cm, 70 to 150cm, or 100 to 200 cm.
In some embodiments, the rounded tip is caused to penetrate into the ITM at a particular penetration depth when the rounded tip is pushed toward the ITM surface and/or vice versa.
In some embodiments, the rounded tip is urged towards the ITM and/or vice versa against a liquid solution disposed in a gap between the rounded tip and a portion of the ITM surface facing the rounded tip, in force balance, thereby maintaining the gap constant.
In some embodiments, the size of the gap adjusts the thickness of the desired uniform thin layer of the treatment formulation.
In some embodiments, the ratio between the gap and the thickness of the desired uniform thin layer is at least 0.1, or at least 0.25, or at least 0.5, and/or at most 10, or at most 4, or at most 2.
In some embodiments, (i) the size of the gap is at most 2 microns, or at most 1 micron, or at most 0.8 microns, or at most 0.6 microns, and/or (ii) the ratio between the size of the gap and the penetration depth of the rounded tip through the ITM surface is at most 0.01, or at most 0.005, or at most 0.001, or at most 0.0005.
In some embodiments, the penetration depth is set to a set point value, and the magnitude of the pushing force is adjusted to maintain the penetration depth at the set point value.
In some embodiments, the radius of curvature of the rounded blade tip is at most 2mm, or at most 1.5mm, or at most 1.25mm, or at most 1mm.
In some embodiments, the coater for coating the ITM is selected from the group consisting of (i) a spray device and (ii) a wetting tray positioned below the lower run of the ITM in which a quantity of the liquid treatment formulation is placed.
In some embodiments, the system includes a cleaning station positioned downstream of the stamping station and upstream of the conditioning station for removing residual material remaining on the ITM surface after transferring the ink image to the substrate.
In some embodiments, the doctor blade is one of a plurality of doctor blades mounted on the circumference of a turret that is rotatable to facilitate replacement of the doctor blade being pushed against the surface.
In some embodiments, the spacing of the blades on the turret circumference is such that during rotation of the turret to change doctor blades, the changed blades do not cease to function until the changing blades are active.
In some embodiments, a blade cleaning device is disposed adjacent to the turret to remove any deposits that adhere to the currently inactive doctor blade.
In some embodiments, a blade cleaning device is disposed adjacent to the turret to remove any deposits that adhere to the currently inactive doctor blade.
In some embodiments, the cleaning device is a rotating brush.
According to various aspects of the present invention, there is provided a printing method comprising a. Providing an aqueous ink, an aqueous treatment formulation and an Intermediate Transfer Member (ITM) having a release surface, b. Applying the aqueous treatment formulation to the release surface of the ITM to form a wet treated layer thereon, c. Subjecting the wet treated layer to a drying treatment to form a drying treated film from the wet treated layer and on the ITM, d. Depositing aqueous ink droplets onto the drying treated film to form an ink image thereon, e. Drying the ink image to leave an ink image residue on the release surface of the ITM, and f. Transferring the ink image residue to a printing substrate by pressure contact between the ITM and the substrate.
In some embodiments, the ink image residue is transferred to the print substrate along with the non-printed areas of the dry processing film.
In some embodiments, the drying treatment film mechanically connects and/or adheres the non-printed areas to the ink image residues during and/or immediately after transfer.
In some embodiments, the drying treatment film is made continuous over a plurality of different substrate-resident ink dots immediately after the ink image remains.
In some embodiments, at least the release surface of the ITM has a shore a hardness of at most 50, or at most 45, or at most 40, or at most 35, or at most 30, or at most 25, or at most 20, or at most 15.
In some embodiments, the ITM is in the form of an endless belt mounted on a plurality of rollers, and the wet-treated layer is formed by applying pressure (e.g., in a normal direction) to the surface of the ITM at a point between the upstream roller and the downstream roller.
In some embodiments, (i) the aqueous treatment formulation is applied to the ITM while the ITM is in operation, thereby causing at least a portion or portions thereof to move at a speed in the range of at least 0.5, or at least 1, or at least 1.5, or at least 2, or at least 2.5, or at least 3 m/s, optionally, at most 5.5 m/s, at most 5.0 m/s, at most 4.5 m/s, at most 4.0 m/s, or at most 3.8 m/s, and typically 0.5 to 5 m/s, 1 to 4.5 m/s, 1 to 4 m/s, 1.5 to 5 m/s, 1.5 to 4.5 m/s, 1.5 to 4 m/s, 2 to 5 m/s, 2 to 4.5 m/s, 2.5 to 4.5 m/s, or 3 to 4.5 m/s, and (ii) the aqueous treatment is applied to one or more portions of the ITM to form a wet treatment thereon.
In some embodiments, the wet treated layer is formed by applying a force to the ITM from a highly rounded surface having a radius of curvature of at most 5mm, or at most 3mm, or at most 2.5mm, or at most 2mm, or at most 1.75mm, or at most 1.5mm, or at most 1.25mm, or at most 1 mm.
In some embodiments, the highly rounded surface is a surface of a doctor blade.
In some embodiments, the doctor blade is oriented in the cross-printing direction and urged toward the ITM with a force density of at least 250g/cm, or at least 350g/cm, or at least 400gm/cm, and/or at most 1kg/cm, or at most 750g/cm, or at most 600g/cm in the cross-printing direction.
In some embodiments, the doctor blade is formed of a wear resistant material having a brinell hardness of greater than 100.
In some embodiments, the doctor blade is smooth and/or has a regular cylindrical surface.
In some embodiments, the doctor blade has a surface roughness RA of at most a few microns, or at most 1 micron, or at most 0.5 microns.
In some embodiments, the doctor blade is one of a plurality of doctor blades mounted on a turret that is rotatable to allow for quick replacement of the doctor blade interacting with the surface of the ITM.
In some embodiments, the spacing of the blades on the turret is such that during rotation of the turret to change the doctor blade, the changed blades do not cease to interact with the ITM before the changed blades begin to interact with the ITM.
In some embodiments, a cleaning device, such as a rotating brush, is disposed near the turret to the rounded edge of at least one blade that is not currently interacting with the ITM.
In some embodiments, wherein the release surface of the ITM is washed to remove any treatment film remaining on the release surface after completion of a previous printing cycle prior to applying the aqueous treatment solution to the release surface of the ITM.
In some embodiments, washing of the release surface of the ITM is performed using an aqueous treatment solution to dissolve any dry treatment film on the release layer.
In some embodiments, the thickness of the wet treated layer is at most 2 μ, or at most 1.5 μ, or at most 1 μ, or at most 0.9 μ, or at most 0.8 μ, or at most 0.7 μ, or at most 0.6 μ, or at most 0.5 μ, or at most 0.4 μ, or at most 0.3 μ, or at most 0.2 μ, or at most 0.15 μ.
In some embodiments, the wet treated layer has a uniform thickness.
In some embodiments, the entire rectangle is covered by the wet-treated film over a rectangle having a width of at least w cm and a length of at least l cm, such that the thickness of the wet-treated film deviates from the average thickness value within the rectangle by no more than 50%, or no more than 40%, or no more than 30%, or no more than 20%, or no more than 10%, or no more than 5%, or no more than 2.5%, or no more than 1%, wherein (i) the value of w is at least 10, or at least 20, or at least 30, and/or at most 100, or at most 80, or at most 60, and (ii) the value of l is at least 50, or at least 100, or at least 250, or at least 500, or at least 1000.
In some embodiments, the forming of the thin wet treated layer includes generating a velocity gradient of the aqueous treatment solution at a strong velocity gradient (IVG) location that is generally displaced (e.g., up to 3 microns, or up to 2 microns, or up to 1 micron) from the stripping surface of the ITM and/or (B) between the applicator and the stripping surface of the applicator, and ii. At the IVG location, the magnitude of the velocity gradient equals or exceeds a VG value of at least 106sec-1, or at least 2X 106sec-1, or at least 4X106sec-1, or at least 5X106 sec-1, or at least 7.5X 106sec-1, or at least 107sec-1, or at least 2X 107sec-1, or at least 4X107sec-1, or at least 5X107sec-1, or at least 7.5X 107sec-1.
In some embodiments, the velocity gradient is positioned in the printing direction such that i.at an upstream location upstream of the IVG location the maximum velocity gradient is at most x of the velocity gradient value at the IVG location ii.at a downstream location downstream of the IVG location the maximum velocity gradient is at most x of the velocity gradient value at the IVG location iii.x has a value of at most 50, or at most 30, or at most 20, or at most 10 and/or iv.the upstream and downstream locations are each displaced in the printing direction from the IVG location by at most 2cm, or at most 1.5cm, or at most 1.25cm, or at most 9mm, or at most 8mm, or at most 7.5mm, or at most 7mm, or at most 6mm, or at most 5mm.
In some embodiments, drying of the treatment solution is performed fast enough to prevent beading and leave a polymer treatment film of continuous hydrophilicity and cohesiveness having a thickness (e.g., a substantially uniform thickness) of at most 200nm, or at most 150nm, or at most 120nm, or at most 100nm, or at most 80nm, or at most 70nm, or at most 60nm, or at most 50nm, or at most 40nm, or at most 30 nm.
However, in various embodiments, even if the drying treatment film is extremely thin, it is thicker than a single layer or a single layer structure. Thus, in various embodiments, the thickness of the dried treatment layer may be at least 20 nanometers, or at least 30 nanometers, or at least 40 nanometers, or at least 50 nanometers. In some embodiments, providing such a 'bulk' (i.e., a minimum thickness feature-e.g., in conjunction with one or more other features described below) facilitates forming a drying treated film having cohesiveness and/or elasticity-which can be used in step S117, wherein it is desirable for the drying treated film (i.e., at that stage, carrying a dried ink image thereon) to maintain its structural integrity when transferred from the ITM to the substrate.
In some embodiments, the thickness of the dried treatment film on which the ink droplets are deposited is at most 200nm, or at most 100nm, or at most 50nm, or at most 30nm.
In some embodiments, the thickness of the dried treatment film on which the ink droplets are deposited is at least 15nm, or at least 20m, or at least 30nm, or at least 50nm, or at least 75nm.
In some embodiments, the drying treatment film is continuous across the rectangle of the peeling surface of the ITM, wherein the rectangle has a width of at least w cm and a length of at least l cm, wherein (i) the value of w is at least 10, or at least 20, or at least 30, and/or at most 100, or at most 80, or at most 60, and (ii) the value of l is at least 50, or at least 100, or at least 250, or at least 500, or at least 1000.
In some embodiments, the drying treatment film is continuous such that the thickness of the drying treatment film deviates from the average thickness value within the rectangle by no more than 50%, or no more than 40%, or no more than 30%, or no more than 20%, or no more than 10%, or no more than 5%, or no more than 2.5%, or no more than 1% for at least 50%, or at least 75%, or at least 90%, or at least 95%, or at least 99%, or 100% of the area of the rectangle.
In some embodiments, during the drying treatment of the wet treated layer, its dynamic viscosity increases by at least 100-fold, or at least 500-fold, or at least 1000-fold, or at least 2500-fold, or at least 5000-fold, or at least 10,000-fold, or at least 25,000-fold over a period of up to 1 second, or up to 500 milliseconds, or up to 250 milliseconds, or up to 150 milliseconds, or up to 100 milliseconds, or up to 75 milliseconds, or up to 50 milliseconds, or up to 25 milliseconds, or up to 15 milliseconds, or up to 10 milliseconds.
In some embodiments, the liquid content of the drying treatment film is at most 10 wt%, or at most 7.5 wt%, or at most 5 wt%, or at most 2.5 wt%, or at most 1.5 wt%, or at most 1 wt%.
In some embodiments, the drying process removes at least 80 wt%, or at least 90 wt%, or at least 95 wt% of the water in the wet treated layer (e.g., over a period of up to 1 second, or up to 0.5 seconds, or up to 100 milliseconds, or up to 50 milliseconds, or up to 25 milliseconds, or up to 10 milliseconds) to form a dry treated film.
In some embodiments, the drying process removes at least 80 wt%, or at least 90 wt%, or at least 95 wt% of the 60 degrees celsius/1 atmosphere liquid of the wet processed layer to form a drying processed film.
In some embodiments, the surface (e.g., upper surface) of the dried treatment film on which the aqueous ink droplets are deposited is characterized by an average roughness Ra (a commonly used one-dimensional average roughness parameter) of at most 30 nanometers, or at most 25 nanometers, or at most 20 nanometers, or at most 18 nanometers, or at most 16 nanometers, or at most 15 nanometers, or at most 14 nanometers, or at most 12 nanometers, or at most 10 nanometers, or at most 9 nanometers, or at most 8 nanometers, or at most 7 nanometers, or at most 5 nanometers, and/or at least 3 nanometers, or at least 5 nanometers.
In some embodiments, the dried treated film on which the aqueous ink droplets are deposited and the surface (e.g., upper surface) of the dried treated film are characterized by a dimensionless ratio between (i) the average roughness Ra and (ii) the thickness of the dried treated layer, wherein the dimensionless ratio is at least 0.02, or at least 0.03, or at least 0.04, or at least 0.05, or at least 0.06, or at least 0.07, or at least 0.08, or at least 0.09, or at least 0.10, or at least 0.11, or at least 0.12, or at least 0.13, or at least 0.14, or at least 0.15, or at least 0.16, or at least 0.17, or at least 0.18, or at least 0.19, or at least 0.2.
In some embodiments, the dried treated film on which the aqueous ink droplets are deposited and the surface (e.g., upper surface) of the dried treated film are characterized by a dimensionless ratio between (i) the average roughness Ra and (ii) the thickness of the dried treated layer, wherein the dimensionless ratio is at most 0.5, at most 0.4, at most 0.3, at most 0.25, at most 0.2, at most 0.15, or at most 0.1, and optionally, at least 0.02, or at least 0.03, or at least 0.04, or at least 0.05, or at least 0.06, or at least 0.07, or at least 0.08.
In some embodiments, the drying treatment film is continuous when dried.
In some embodiments, the aqueous treatment formulation is provided in the form of a solution.
In some embodiments, the aqueous treatment formulation is provided in the form of a dispersion.
In some embodiments, wherein the solids of the aqueous ink (e.g., nanopigments and/or resins) migrate into the bulk of the drying treatment film to interact with (e.g., bind to) the quaternary ammonium salt residing within the drying treatment film (e.g., to facilitate droplet spreading).
In some embodiments, the substrate is selected from the group consisting of an uncoated fibrous print substrate, a commercially coated fibrous print substrate, and a plastic print substrate.
In some embodiments, the printing substrate is paper, optionally selected from the group of papers consisting of bond paper, uncoated offset paper, coated offset paper, copy paper, mill paper, coated mill paper, wood-free paper, coated wood-free paper, and laser paper.
In some embodiments, the transferring is performed at a transfer temperature of at most 120 ℃, or at most 100 ℃, or at most 90 ℃, or at most 80 ℃.
In some embodiments, the solids of the aqueous ink (e.g., nanopigments and/or resins) migrate into the bulk of the drying treatment film to interact with (e.g., bind to) the quaternary ammonium salt residing within the drying treatment film.
In some embodiments, the method is performed such that a set of ink dots IDS of ink substrate-resident ink dots is formed.
In some embodiments, the method is performed such that the plurality of droplets DP of the aqueous ink droplets deposited onto the ITM-resident dried treatment film form a set of ink spots IDS of ink substrate-resident ink spots, such that there is correspondence between (i) each given droplet of the plurality of droplets DP and (ii) a respective given substrate-resident ink spot of the set of ink spots, such that a given droplet is generated and/or evolved into a given substrate-resident ink spot.
In some embodiments, the method is performed such that, during deposition, whenever a droplet of the plurality of droplets collides with a drying treatment film on the ITM, the kinetic energy of the impinging droplet deforms the droplet.
In some embodiments, the method is performed such that (i) the maximum impact radius of each deformed droplet on the ITM surface has a maximum impact radius value R maximum impact and (ii) the physicochemical forces spread the deformed droplet or dot resulting therefrom after impact and/or during transfer and/or after transfer, thereby causing each ink dot of the set of ink dots IDS where the substrate resides to have a dry dot radius R dry spots on the substrate;
(iii) For each of the plurality of drops and a corresponding ink point of the ink point set IDS, at
I. the substrate residence dry point radius R dry spots on the substrate, and
Maximum impact radius value R of the deformed droplet maximum impact
The ratio therebetween is at least 1, or at least 1.01, or at least 1.02, or at least 1.03, or at least 1.04, or at least 1.05, or at least 1.1, or at least 1.15, or at least 1.2, or at least 1.25, or at least 1.3, or at least 1.35, or at least 1.4, or at least 1.45, or at least 1.5, and optionally at most 2, at most 1.8, at most 1.7, at most 1.6, or at most 1.55.
In some embodiments, the method is performed such that i. a plurality of droplets DP of the droplets deposited onto the ITM resident drying treatment film produce a set of substrate resident ink points IDS (i.e., fixedly adhered to a top substrate surface), each droplet of the plurality of droplets DP corresponding to a different respective substrate resident ink point of the set of ink points IDS; depositing each droplet of the plurality of droplets DP onto the substrate according to a jetting parameter, iii. The jetting parameter together with the physicochemical properties of the droplet of the plurality of droplets DP define an inkjet paper dot radius R direct spraying onto ink-jet paper, which is the radius of the ink dot obtained by jetting the droplet directly onto inkjet paper instead of onto the drying treatment film, and iv. The ratio between (a) the dry dot radius R dry spot on substrate of the ink dot set IDS and (B) the inkjet paper dot radius R direct spraying onto ink-jet paper, theory of is at least 1, or at least 1.01, or at least 1.02, or at least 1.03, or at least 1.04, or at least 1.05, or at least 1.1, or at least 1.15, or at least 1.2, or at least 1.25, or at least 1.3, or at least 1.35, or at least 1.4, or at least 1.45, or at least 1.5, and optionally at most 2, at most 1.8, at most 1.7, at most 6, or at most 1.55.
In some embodiments, the cardinality of the set of ink dots is at least 5, or at least 10, or at least 20, or at least 50, or at least 100, each ink dot of the set of ink dots being different on the substrate.
In some embodiments, the method is performed such that the ink dots of a set of ink dots are contained within a square geometric projection projected onto the print substrate, each ink dot of the set of ink dots being fixedly adhered to the surface of the print substrate, all of the ink dots within the square geometric projection being counted as individual members of the set of ink dots IDS.
In some embodiments, the method is performed such that each of the ink dots comprises at least one colorant dispersed in an organic polymer resin, each of the dots having an average thickness of less than 2,000nm and a diameter of 5 microns to 300 microns.
In some embodiments, the method is performed such that each of the ink dots has a generally convex shape, wherein the deviation from convexity (DC Point(s)) is defined by the formula DC dot = 1-AA/CSA, AA being the calculated projected area of the dot, the area being disposed generally parallel to the print substrate, and CSA being the surface area of the convex shape that minimally defines the outline of the projected area, wherein the average deviation from convexity of the set of ink dots (DC Point average) is at most 0.05, at most 0.04, at most 0.03, at most 0.025, at most 0.022, at most 0.02, at most 0.018, at most 0.017, at most 0.016, at most 0.015, or at most 0.014.
In some embodiments, the method is performed such that each dot contains at least one colorant dispersed in an organic polymer resin, each dot covers a continuous region of the top surface of the substrate, each dot is disposed entirely above the continuous region such that (i) a projected vertical line extending down toward the top substrate surface first meets the dot at each point in the continuous region before encountering the top substrate surface, and/or (ii) each dot has a diameter of 15 microns to 300 microns, and/or (iii) each of the dots has an average thickness of at most 1,800nm, each of the dots is characterized by a dimensionless aspect ratio (R Longitudinal and transverse directions)：R Longitudinal and transverse directions＝D Point(s)/H Point(s)) defined by the formula wherein D Point(s) is the diameter, and H Point(s) is the average thickness, and/or (iv) the aspect ratio is at least 50, or at least 60, or at least 75, or at least 95, or at least 110, or at least 135, or at least 170, or at least 180, or at least 170, or at least 200, or at least 170, or at least 200 or at least 300, or at least 220 or at least 200, or at least 300.
In some embodiments, the method is performed such that the aspect ratio is at most 400, at most 350, or at most 325.
In some embodiments, the method is performed such that each dot contains at least one colorant dispersed in an organic polymer resin, each dot covers a continuous region of a top surface of a substrate, each dot is disposed entirely above the continuous region such that (i) a projected vertical line extending down toward the top substrate surface first meets the dot at each point in the continuous region before encountering the top substrate surface, and/or (ii) each dot has a diameter of 15 micrometers to 300 micrometers, and/or (iii) each of the dots has an average thickness of at most 1,800nm, each of the dots is characterized by a dimensionless aspect ratio (R Longitudinal and transverse directions)：R Longitudinal and transverse directions＝D Point(s)/H Point(s), wherein D Point(s) is the diameter, and H Point(s) is the average thickness), and/or (iv) the aspect ratio is in the range of 140 to 400, 150 to 300, 160 to 300, 180 to 300, 200 to 300, 220 to 300, 230 to 300, 300 to 300, or 240 to 300.
In some embodiments, the method is performed such that at least one of the ink dots of an ink drop set IDS (or at least a majority or all) contains less than 2% charge director.
In some embodiments, the method is performed such that at least one of the ink points of an ink drop set IDS (or at least a majority or all) is free of a charge director.
In some embodiments, the method is performed such that at least one of the ink dots of an ink dot set IDS (or at least a majority or all) has a thickness of at most 1,500nm, or at most 1000nm, or at most 800nm, or at most 600nm, or at most 400nm, or at most 350nm, or at most 300nm, or at most 250 nm.
In some embodiments, the method is performed such that at least one of the ink points of an ink drop set IDS (or at least a majority or all) contains at least 1.2 wt% of the colorant.
In some embodiments, the method is performed such that at least one of the ink points of an ink-drop set IDS (or at least a majority or all) contains at least 5 wt% of the resin.
In some embodiments, the method is performed such that at least one of the ink dots (or at least a majority or all) of the set of ink dots IDS is such that the total concentration of the colorant and the resin within the ink dots is at least 40%.
In some embodiments, the method is performed such that the weight ratio of the resin to the colorant within the ink dot is at least 1:1.
In some embodiments, the method is performed such that the ink dots of an ink dot set IDS are such that there is no adhesive failure when subjected to standard tape testing.
In some embodiments, the method is performed such that the surface concentration of nitrogen at the surface on the film of each of the ink dots exceeds the bulk concentration of nitrogen within the film, the bulk concentration measured at a depth of at least 30 nanometers below the film upper surface, and wherein the ratio of the surface concentration to the bulk concentration is at least 1.1 to 1.
In some embodiments, the method is performed such that the film upper surface of each ink dot exhibits an X-ray photoelectron spectroscopy (XPS) peak at 402.0+ -0.4 eV.
In some embodiments, the method is performed such that the ink dots of the ink drop set have a first dynamic viscosity in the range of 106 cP to 3.108 cP in the range of 90 ℃ to 195 ℃.
In some embodiments, the method is performed such that the first dynamic viscosity is at most 7.107 cP.
In some embodiments, the method is performed such that the first dynamic viscosity is in the range of 106 cP to 108 cP.
In some embodiments, the method is performed such that the first dynamic viscosity is at least 4.106 cP.
In some embodiments, the method is performed such that at least one ink dot (or at least a majority or all ink dots) is a plurality of consecutive ink dots.
In some embodiments, the method is performed such that for at least one ink dot (or at least a majority or all of the ink dots), the dot thickness is at most 1,200nm, or at most 1,000nm, or at most 800nm, or at most 650nm, or at most 500nm, or at most 450nm, or at most 400nm.
In some embodiments, the method is performed such that the ITM is any ITM disclosed herein and/or the aqueous treatment solution is any aqueous treatment solution disclosed herein.
In some embodiments, the aqueous ink comprises a pigment, a binder, a dispersant, and at least one additive.
Detailed Description
The invention is described herein by way of example only and with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for a fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice. Like reference characters generally refer to like elements throughout the drawings.
Definition of the definition
Within the present application, the following terms are to be understood as having the following meanings:
a) The term "receding contact angle" or "RCA" refers to a receding contact angle measured using a DATAPHYSICS OCA Pro contact angle measurement device or similar video-based optical contact angle measurement system using a drop shape method. Similar "advancing contact angle" or "ACA" refers to an advancing contact angle measured in substantially the same manner.
B) The term "standard aging procedure" refers to an accelerated aging regimen performed in a standard convection oven at 160 ℃ for 2 hours for each peel ply tested.
C) The term "standard air cure" refers to a conventional curing process for curing a release layer wherein the release layer surface (or "ink receiving surface") is exposed to air during the curing of the release layer.
D) The term "bulk hydrophobicity" is characterized by the receding contact angle of a distilled water droplet disposed on the inner surface of the lift-off layer, which is formed by exposing regions of cured silicone material within the lift-off layer.
E) The term "image transfer member" or "intermediate transfer member" or "transfer member" refers to a component of a printing system on which ink is initially applied by a printhead, such as by an inkjet head, and then transferred to another substrate or substrates, typically the final printed substrate.
F) The term "blanket" refers to a flexible transfer member that may be installed within a printing device to form a belt structure on two or more rollers, wherein at least one roller is capable of rotating and moving the blanket (e.g., by moving its belt) to travel around the roller.
G) The term "on the release surface" with respect to an object such as an ink image or ink residue means supported by and/or above the release surface. The term "on the release surface" does not necessarily mean direct contact between the ink image or ink residue and the release surface.
H) The term "having a static surface tension sufficiently high to increase the static surface tension of the aqueous treatment formulation" and the like with respect to a particular surfactant within the aqueous treatment formulation is assessed by adding additional amounts or aliquots of the particular surfactant to the formulation and comparing the resulting static surface tension of the formulation to the static surface tension of the formulation prior to the addition of those aliquots.
I) The term "liquid absorbent" refers to an absorbent that is liquid at least one temperature in the range of 25 ℃ to 90 ℃ and has a vapor pressure of at most 0.05ata, and more typically at most 0.02ata, at most 0.01ata, or at most 0.003ata in the pure state and at 90 ℃. The term "liquid moisture absorbent" refers in particular to materials such as glycerol.
J) The terms "hydrophobic" and "hydrophilic" and the like may be used in a relative sense and are not intended to be absolute.
K) The term '(treatment) formulation' refers to a solution or dispersion.
L) the evaporation load is now defined as x degrees celsius, where x is a positive number. When the solution is y% solids weight and z% liquid weight at x degrees celsius, the 'x-degree celsius evaporation load' of the solution is the z/y ratio. The unit of the 'evaporation load' is "solvent weight/total solute weight". For the purposes of this disclosure, the evaporation load is always defined at atmospheric pressure. For purposes of this disclosure, the term 'evaporation load' where the default value of 'x' is 60 degrees celsius-no prefix of the specified temperature refers to an evaporation load of 60 degrees celsius at atmospheric pressure.
M) when a portion of the ITM is running at a speed of v m/s, this means that a portion of the blanket ITM is moving in a direction parallel to its local surface/plane at a speed of at least v m/s-for example with respect to a stationary applicator.
N) the term 'static surface tension' refers to the static surface tension at 25 ℃ and atmospheric pressure.
O) the term 'thickness' of the wet layer is defined as follows. When a volume of vol material covers a surface area of a surface having an area SA with a wet layer, the thickness of the wet layer is assumed to be vol/SA.
P) the term 'thickness' of the dry film is defined as follows. When a volume of vol x wt% liquid material wets or covers the surface area SA of the surface and all liquid is evaporated to convert the wet layer to a dry film, the thickness of the dry film is assumed to be
vol/ρ Wet layer(100-x)/()SA·ρ Dry layer)
Where ρ Wet layer is the specific gravity of the wet layer and ρ Dry layer is the specific gravity of the dry layer.
Q) the term 'continuous wet layer' refers to a continuous wet layer covering the convex region without any uncovered sub-regions within the perimeter of the convex region.
R) the term 'continuous thin dry film' refers to a continuous dry film that covers the convex area without any discontinuities within the perimeter of the convex area.
S) the term 'cohesive film/tensile strength' refers to the structure that remains together when peeled from the surface to which it is adhered-i.e. when peeled from the surface, the 'cohesive film' retains its structural integrity and is peeled as a skin rather than splitting into small pieces.
T) the term 'normally applied force' refers to a force having at least one component in the normal direction-and optionally, the 'normally applied' force may have additional components in other directions (e.g., along the surface to which the force is applied).
U) physical properties of a liquid (e.g., a treatment formulation), such as viscosity and surface tension, refer to properties at 25 ℃, unless otherwise specified.
V) unless otherwise indicated, 'concentration' refers to weight-i.e., the weight of a formulation component/the total weight of the formulation.
Discussion of FIG. 2
Fig. 2 is a flow chart of a method of indirectly printing onto a silicone-based release subsequent surface of an Intermediate Transfer Member (ITM) with aqueous ink. In some embodiments, the method of FIG. 2 (or any combination of steps thereof) may be performed using the apparatus (or one or more components thereof) disclosed in FIGS. 3A-3B, 4A-4B, 5-9, 10A-10C, and 11A-11C. In particular, and as will be discussed below, embodiments of the present invention relate to methods and apparatus that can be used to produce a wet processed layer of uniform sub-micron thickness on a large area of ITM and/or at high printing speeds.
In various embodiments, FIG. 2 may be performed to generate an ink image characterized by any combination of uniform and controlled dot gain, good and uniform print gloss, and good image quality due to high quality dots having consistent dot convexities and/or well-defined boundaries.
Steps S201-S205 relate to ingredients or components or consumables used in the printing process of fig. 2, while steps S209-S225 relate to the process itself.
Briefly, the steps of FIG. 2 are as follows, in steps S201 and S205, ITM (i.e., including a silicone-based release layer surface) and an aqueous treatment formulation (e.g., solution), each having the specific properties discussed below, are provided. In step S209, an aqueous treatment formulation is applied to the release layer surface of the ITM to form a wet treatment layer thereon. In step S213, the wet processed layer is subjected to a drying process, thereby forming a drying processed film on the ITM. In step S217, droplets of aqueous ink are deposited onto the drying treatment film to form an ink image on the ITM surface. In step S221, the ink image is dried to leave an ink image residue on the ITM surface, and in step S225, the ink image residue is transferred to a print substrate.
Embodiments of the present invention relate to methods, devices and kits for achieving potentially competing goals of dot gain, image gloss and dot quality, preferably in a production environment where high printing speeds are critical. According to some embodiments, the inventors have found that it is useful to perform the method of fig. 2, thereby making the dried treated film formed in step S213 very thin (e.g., up to 150 nanometers, or up to 120 nanometers, or up to 100 nanometers, or up to 80 nanometers, or up to 70 nanometers, or up to 60 nanometers, or up to 50 nanometers, and optionally, at least 20 nanometers or at least 30 nanometers) and/or continuous over a large area and/or characterized by a very smooth upper surface and/or being rich in quaternary ammonium salt (e.g., to promote dot gain) and/or having properties that promote good transfer from ITM to the substrate (i.e., the film itself or the properties of the film relative to the ITM surface).
For example, thicker treatment films may negatively impact their gloss or uniformity because, after transfer, dried ink residues may reside under the treatment film and on the substrate surface. Therefore, a very thin treatment film can be preferably produced.
For example, the discontinuity of the treatment film and/or the treatment film of different thickness may produce an image of uneven gloss on the substrate, or may produce an ink image residue that loses its mechanical integrity when transferred to the substrate (in step S113). Thus, it may be preferred to produce a treated film that is continuous over a large area-preferably, cohesive enough to maintain structural integrity and/or to have thermal rheological properties on the printed substrate, so that the treated film is tacky at transfer temperatures between 75 degrees celsius and 150 degrees celsius.
For example, the presence of quaternary ammonium salts in the drying treatment film can promote spreading of ink droplets, but does not have to be uniform droplet spreading. However, a combination of (i) a high concentration of quaternary ammonium salt in the dried treatment film and (ii) a treatment film of uniform thickness having a very smooth upper surface can promote uniform ink droplet spreading.
Embodiments of the present invention relate to techniques for achieving these results simultaneously, even though they require potential competing goals. For example, it is required that the handling film be very thin so that it is more challenging to form a handling film that is continuous over a large area and/or has sufficient cohesiveness to transfer well to a substrate and/or has a very smooth and uniform upper surface.
Discussion of step S201
Although the ITM provided in step S201 has a silicone-based release layer, its release surface may be less hydrophobic or significantly less hydrophobic than many conventional silicone-based release layers. The structural properties may be measured and characterized in various ways.
For example, as shown in step S201 of FIG. 2, the Intermediate Transfer Member (ITM) comprises a silicone-based release layer surface having sufficient hydrophilicity to satisfy at least one of (i) a receding contact angle of a distilled water droplet deposited on the silicone-based release layer surface of at most 60 DEG, and (ii) a 10-second Dynamic Contact Angle (DCA) of a distilled water droplet deposited on the silicone-based release layer surface of at most 108 deg.
Any of a number of techniques for reducing the hydrophobicity of the silicone-based release layer may be employed.
In some embodiments, polar functional groups are incorporated into and/or generated in the silicone-based release layer. In one embodiment, functional groups may be added to the pre-polymer batch (e.g., monomers in solution) -these functional groups may become part of the silicone polymer network upon curing. Alternatively or additionally, the silicone-based release layer is pre-treated (e.g., by corona discharge, or by electron beam) to increase its surface energy.
Alternatively, the silicone-based release layer may be fabricated to have reduced hydrophobicity even when substantially free of functional groups. In one embodiment, the silicone polymer backbone of the release layer can be configured such that its polar groups (e.g., O-Si-O) are oriented in a direction normal to a local plane of the ITM surface and face 'up' toward the release layer surface.
To date, the present inventors believe that the technique of the previous paragraph can provide excellent image transfer (step S225).
Discussion of step S205 of FIG. 2
One feature of the aqueous treatment formulation provided in step S205 is that the static surface tension of the aqueous treatment formulation is in the range of 20 dynes/cm and 40 dynes/cm. For example, the aqueous treatment formulation comprises one or more surfactants.
Thus, the aqueous treatment formulation of step S205 is not as hydrophilic as many conventional treatment solutions, and is significantly less hydrophilic than water.
In some embodiments, the combination of (i) a silicone-based release layer having reduced hydrophobicity (step S201) and (ii) an aqueous treatment formulation having reduced hydrophilicity reduces (but does not necessarily eliminate) the surface tension effect that promotes beading of conventional aqueous treatment solutions.
In addition to static surface tension in the range of 20 dynes/cm and 40 dynes/cm, the aqueous treatment formulation provided in step S205 has the following properties:
a. the aqueous treatment formulation comprises at least 3% by weight of quaternary ammonium salt. This may be used to ensure that the drying treatment film (i.e., produced in step S217) is rich in quaternary ammonium salt, which may be used to promote good spot gain;
b. The aqueous treatment formulation comprises at least 1 wt% (e.g., at least 1.5 wt%, or at least 2 wt%, or at least 3 wt%) of at least one water-soluble polymer having a solubility in water of at least 5% at 25 ℃. This may be used to facilitate the formation of a polymer film or matrix in the drying process film (generated in step S217) that has sufficient cohesiveness to achieve good transfer in step 225.
The dynamic viscosity at 25 ℃ is at least 10cP. As discussed below, it is believed that the elevated viscosity can be used to counteract any surface tension driven beading tendency.
D. An evaporation load of at most 8:1 (e.g., at most 7:1, or at most 6:1, or at most 5:1, or at most 4:1) by weight at 60 ℃. Thus, the solution has a low specific heat capacity relative to conventional treatment formulations having a higher evaporation load. Furthermore, for a particular necessary residue thickness of the aqueous treatment solution, and for a given heat output delivered to the aqueous treatment solution, the viscosity of the aqueous treatment formulation will increase rapidly with evaporation to achieve a high absolute viscosity effective to counteract surface tension.
Physically, it is more difficult to induce fluid flow with higher viscosity than fluid with lower viscosity-i.e., a greater driving force is required in order to induce flow of fluid with higher viscosity. The combination of at least a moderate initial viscosity (i.e., 25 ℃ dynamic viscosity of at least 10 cP) and a rapid viscosity increase after evaporation on the ITM surface (e.g., due to low evaporation load) ensures that the aqueous treatment formulation reaches a relatively higher' (e.g., at least 10,000 cP) viscosity in a relatively short time (e.g., up to 1 second or up to 0.5 seconds). Therefore, even if there is some thermodynamic tendency toward beading, the actual beading that may adversely affect the properties of the dried treatment film (i.e., formed in step S213) can be suppressed or significantly reduced.
In some embodiments, the 25 ℃ dynamic viscosity of the initial aqueous treatment formulation may be at least 12cP, or at least 14 cP-e.g., in the range of 10cP to 100cP, 12cP to 100cP, 14cP to 100cP, 10cP to 60cP, or 12cP to 40 cP.
Summarizing, the combination of (A) a release layer having sufficient hydrophilicity to satisfy at least one of (i) a receding contact angle of distilled water droplets deposited on the surface of the silicone-based release layer of at most 60 DEG and (ii) a 10-second Dynamic Contact Angle (DCA) of distilled water droplets deposited on the surface of the silicone-based release layer of at most 108 DEG, and (B) a static surface tension of the aqueous treatment formulation in the range of 20 dynes/cm to 40 dynes/cm is useful for minimizing the magnitude of thermodynamic driving force that would cause beading. In addition, the viscosity-related features described above may be used to counteract such driving forces.
The reduction in the magnitude of the thermodynamic forces driving the beading and the counteracting of the trend ensure that any beading tendency does not interfere with the formation of the wet treatment formulation layer in step S209 having a uniform thickness in step S209.
In embodiments of the invention, the aqueous treatment formulation comprises an aqueous carrier liquid, the water comprising at least 65% by weight (e.g., at least 70% by weight or at least 75% by weight) of the aqueous treatment formulation;
Discussion of step S209
In step S209, an aqueous treatment formulation is applied to the silicone-based release layer surface of the ITM to form a wet treatment layer thereon having a thickness of at most 0.8 μm (e.g., at most 0.7 μm, or at most 0.6 μm, or at most 0.5 μm).
"Thickness of the wet layer" is defined as assuming that the thickness of the wet layer is vol/SA when a volume of vol material covers a surface area of the surface having area SA with the wet layer.
Preferably, step S209 is performed, whereby the wet treated layer has a uniform thickness and is preferably defect free over a large area, e.g. over the entire area of the release layer. This can be particularly challenging when the wet treated layer has a sub-micron thickness.
As noted above, it is useful that the aqueous treatment formulation have at least a 'moderate viscosity' (e.g., a 25 ℃ dynamic viscosity of at least 10 cP) to counteract beading. However, at such viscosities, there may be challenges associated with obtaining a uniform sub-micron thickness of the aqueous treatment formulation.
In step S209, an aqueous treatment formulation is applied to the surface of the silicone-based release layer to form a wet treated layer having a thickness of at most 0.8 μm.
Embodiments of the present invention relate to apparatus and methods for applying the wet-treated layer, thereby making the thickness preferably uniform over a large area of ITM.
In some embodiments, after coating the ITM surface with the initial coating of the aqueous treatment formulation, the excess treatment formulation may be removed from the initial coating or a wet treatment layer having a uniform thickness of up to 0.8 μm may be obtained.
In some embodiments, this can be achieved by pushing a highly rounded surface (e.g., of a doctor blade) toward the ITM, or vice versa. For example, the radius of curvature of the highly rounded surface may be at most 1.5mm, or at most 1.25mm, or at most 1mm.
At high printing speeds (e.g., where the surface speed of the ITM is relatively large (e.g., at least 1 meter/second, or at least 1.25 meter/second, or at least 1.5 meter/second), removing excess liquid to form a treated layer having a sub-micron thickness may require establishing a relatively large speed gradient (i.e., shear) in the gap region between the elevation surface and the ITM (e.g., the speed gradient being normal to the ITM surface), such as a speed gradient of at least 106sec-1 or at least 2x 106sec-1.
As described above, the 25 ℃ dynamic viscosity of the treatment formulation may be at least 10cP. Even if step S209 is performed at higher temperatures, the dynamic viscosity at these higher temperatures may be at least 3cP, or at least 5cP, or at least 10cP. Thus, in some embodiments of the invention, relatively large forces (e.g., pushing a highly rounded surface toward the ITM or vice versa) are required to achieve the desired uniform sub-0.8 μm (preferably) uniform thickness.
In some embodiments, the rounded surface is urged toward the ITM in the cross-printing direction with a force density of at least 250g/cm, or at least 350g/cm, or at least 400gm/cm, and/or up to 1kg/cm, or up to 750 g/cm, or up to 600g/cm, or vice versa.
In some embodiments, the wet treatment layer is formed by applying a compressive force between the applicator and the ITM, the magnitude of the compressive force being at least 0.1 bar, or at least 0.25 bar, or at least 0.35 bar, or at least 0.5 bar, and optionally at most 2 bar, or at most 1.5 bar, or at most 1 bar.
Discussion of step S213
In step S213, the wet-processed layer is subjected to a drying process, thereby forming a drying-processed film.
For example, during the drying treatment of the wet treated layer, its dynamic viscosity increases by at least 1000 times over a period of up to 0.5 seconds or up to 0.25 seconds.
In some embodiments, the thickness of the dry treated film (e.g., the cohesive polymer treated film) is at most 150 nanometers, or at most 120 nanometers, or at most 100 nanometers, or at most 80 nanometers, or at most 60 nanometers.
In some embodiments, the drying treatment film has a smooth upper surface. For example, the drying treatment of the wet treated layer is fast enough, whereby the viscosity of the aqueous treatment formulation is rapidly increased enough to suppress surface tension-driven beading, and thus the dried treated film has a smooth upper surface.
In some embodiments, the smooth upper surface of the dried treated film is characterized by an average roughness Ra of at most 12 nanometers, or at most 10 nanometers, or at most 9 nanometers, or at most 8 nanometers, or at most 7 nanometers, or at most 5 nanometers. The skilled person refers to fig. 13 and the accompanying discussion.
In some embodiments, the drying treatment film is continuous across the rectangle of the release surface of the ITM, wherein the rectangle has a width of at least 10cm and a length of at least 10 m.
In some embodiments, the treatment film is transparent.
One of the purposes of drying the treated film is to protect the ITM surface from direct contact with aqueous ink droplets deposited on the treated film. However, the aqueous ink droplets may 'erode' the thickness of the drying treatment film, particularly when the drying treatment film is thin (e.g., at most 150 nanometers, or at most 120 nanometers, or at most 100 nanometers, or at most 80 nanometers). Thus, in some embodiments, an aqueous treatment formulation (e.g., in step S205 of fig. 2 or in step S95 of fig. 12) is provided having a water-soluble polymer concentration of at most 10 wt%, or at most 8 wt%, or at most 6 wt%, or at most 5 wt% of the water-soluble polymer.
Discussion of steps S217-S221
In step S217, droplets of aqueous ink are deposited (e.g., by droplet deposition) onto the drying treatment film to form an ink image on the ITM surface. In step S221, the ink image is dried to leave an ink image residue on the ITM surface.
For example, the presence of quaternary ammonium salt in the dried treatment film can be used to promote dot spread and/or dot gain (e.g., uniform dot spread and/or dot gain) at or immediately after droplet deposition—the skilled artisan mentions the discussion below with reference to fig. 13A-13E. As described above, the formation of a dry-treated film having a uniform thickness and/or no defects and/or having a very smooth upper surface (in step S213) may facilitate a uniform flow of aqueous ink over the upper surface of the film.
Discussion of step S225
In step SS25, the ink image residue is transferred to a substrate. For example, the ink image residue may be transferred to a print substrate along with the non-printed areas of the drying process film.
In embodiments, the drying treatment film has sufficient cohesiveness such that during transfer of the ink image residue, the drying treatment film is completely separated from the ITM and transferred with the dried ink image onto the print substrate in both the printed and non-printed areas.
In some embodiments, the temperature of the ITM during transfer is in a range between 80 ℃ and 120 ℃. In some embodiments, the ITM temperature is at most 100 ℃ or at most 90 ℃. In some embodiments, the ITM temperature is at least 100 ℃, or at least 110 ℃, or at least 120 ℃.
In some embodiments, the presence of the water-soluble polymer in the aqueous treatment solution provided in step S205 helps ensure (i.e., by forming a polymer film or matrix) that the dried treatment film formed in step S213 has sufficient cohesiveness during transfer.
In some embodiments, the substrate of the ink image residue is a glossy paper, such as a glossy coated paper.
The transfer may be perfect (i.e., the ink image residue and the drying treatment film are transferred integrally to the substrate). Alternatively, the transfer may be imperfect-to this end, the cleaning station may remove material remaining on the ITM surface after the transfer step of S225.
Discussion of FIGS. 3A-3B
Fig. 3A is a schematic diagram of a system for indirect printing according to some embodiments of the invention. The system of fig. 3A includes an Intermediate Transfer Member (ITM) 210 comprising a flexible endless belt mounted on a plurality of guide rollers 232, 240, 250, 253, 242. In other embodiments (not shown), the ITM 220 is a drum or a belt wrapped on a drum.
In the embodiment of fig. 3A, the ITM 210 (i.e., its belt) moves in a clockwise direction. The direction of belt movement defines an upstream direction and a downstream direction. Rollers 242, 240 are positioned upstream and downstream, respectively, of image forming station 212-thus, roller 242 may be referred to as an "upstream roller" and roller 240 may be referred to as a "downstream roller".
The system of fig. 3A further includes:
(a) The image forming station 212 (e.g., comprising print bars 222A-222D, wherein each print bar comprises one or more inkjet heads) is configured to form an ink image (not shown) on a surface of the ITM 210 (e.g., by depositing droplets on a drying process film-see, e.g., step S217 of fig. 2 or step S109 of fig. 12);
(b) A drying station 214 for drying the ink image (see, for example, step S221 of fig. 2 or step S113 of fig. 12)
(C) An embossing station 216 in which an ink image is transferred from the surface of the ITM 210 onto a sheet or web substrate (see, e.g., step S225 of fig. 2 or step S117 of fig. 12).
In the particular non-limiting embodiment of fig. 3A, the impression station 216 includes an impression cylinder 220 and a blanket cylinder 218 carrying a compressible blanket 219. In some embodiments, a heater 231 may be provided shortly before the nip between the two rollers 218 and 220 of the image transfer station to help make the ink film tacky to facilitate transfer to a substrate (e.g., a sheet substrate or web substrate). The substrate feed is schematically shown.
(D) A cleaning station 258 (i.e., schematically shown as a block in fig. 3A) in which residual material (e.g., a process film and/or ink image or portions thereof) is cleaned from the surface of the ITM 210 (the cleaning step not shown in fig. 2).
(E) A processing station 260 (i.e., schematically shown as a box in fig. 3A) in which a layer (e.g., having a uniform thickness) of a liquid treatment formulation (e.g., an aqueous treatment formulation) is formed on the ITM surface (e.g., see step S209 of fig. 2 or step S101 of fig. 12).
Those skilled in the art will appreciate that not every component shown in FIG. 3A is required.
Fig. 3B shows a plurality of 'locations' LocA-LocJ,LocA located at the roller 242, locB at the 'start' of the imaging station 212, locC at the 'end' of the imaging station 212, and so on, fixed in space. Accordingly, at the image forming station 212 on the upper run of the ITM 210, an ink image is formed in the region between locations LocA and LocB (e.g., in step S217 of fig. 2). The ink image is dried in the region between locations LocC and LocE (see, e.g., step S221 of fig. 2 or step S105 of fig. 12) to form an ink image residue-this can occur as the ink image moves (e.g., due to clockwise rotation of the ITM) through the drying station 214. The ink image residue is transferred from the ITM surface to the substrate at the imprint station 216 between locations LocE and LocF (see, e.g., step S225 of fig. 2 or step S117 of fig. 12). The material remaining on the surface of the ITM 210 after transferring the ink image residue may be removed from the surface of the ITM 210 at a cleaning station 258 between LocG and LocH. A wet treated layer may be formed on the surface of the ITM 210 at the treatment station 260 between locations LocI and LocJ in step S209 of fig. 2 (or step S101 of fig. 12) (see, e.g., step S209 of fig. 2 or step S101 of fig. 12). Subjecting the wet treated layer to a drying process (i.e., converting the wet treated layer to a drying treated film) (see, e.g., step S213 of fig. 2 or step S105 of fig. 12) -this may occur between locations LocJ and LocA on the right hand side. After the drying process film is transferred (e.g., by counterclockwise rotation of the ITM 210) to the image forming station 212, an ink image may then be formed by droplet deposition onto the drying process film (e.g., see step S217 of fig. 2 or step S109 of fig. 2).
As shown in fig. 3A-3B, the portion of the ITM between locations LocA and LocD is the upper run of the ITM 210 (i.e., its belt). The upper run (shown in fig. 3C) is between (i) an upstream guide roller 242 upstream of the image forming station 212 and (ii) a downstream guide roller 240 downstream of the image forming station. The upper run passes through the image forming station 212.
The lower stroke of the ITM is between positions LocD and LocA of the ITM 210 and is shown in fig. 3D. The lower run passes through the embossing station 216, the cleaning station 258, and the processing station 260.
An example of a processing station is shown in fig. 4A.
In the particular non-limiting embodiment of fig. 4A, the ITM 210 moves as viewed from right to left (as indicated by arrow 2012) over a doctor blade, generally designated as 2014, and is appropriately mounted within the tank 2016. In fig. 4A, the doctor 2014 is of the doctor blade bar type and is formed by a rigid bar or bracket 2020 extending across the width of the ITM 210. In its upper surface facing the underside of the ITM 210, a rod 2020 is formed with channels or grooves 24, within which channels or grooves 24 a rod 2022 made of fused silica and having a smooth and regular cylindrical surface with a roughness of not more than a few microns, preferably less than 10 microns and in particular less than 0.5 microns is supported.
The underside of the ITM 210 (or lower run) is coated with an excess of a treatment formulation (e.g., solution) 2030 (e.g., provided in step S205 of fig. 2 or step S95 of fig. 12) prior to passing through the doctor blade 2014. The manner in which the excess treatment formulation (e.g., solution) is applied to the ITM 210, particularly on the underside thereof, is described below with reference to fig. 5, but is not critical to the invention. The ITM 210 may, for example, simply be immersed in a tank containing liquid, passed through a fountain of treatment formulation (e.g., solution), or sprayed with an upwardly directed jet 1128 as shown in fig. 5.
In one embodiment of the invention, a liquid permeable cloth is placed over an upwardly directed spray head, whereby the liquid permeates the cloth and forms a layer on the side of the cloth facing the surface to be coated. In this case the spray head will be used to push the cloth towards the surface, but the contact with the surface will be prevented by the liquid penetrating it, which acts in the same way as a hydrodynamic bearing.
As shown, when the ITM 210 is proximate to the doctor blade 2014, it has a coating 2030 of liquid, the coating 2030 being significantly greater than the desired thickness of film to be applied to the ITM 210.
The function of the doctor 2014 is to remove excess liquid 2030 from the ITM 210 and ensure that the remaining liquid spreads evenly and uniformly across the entire surface of the ITM 210. To achieve this, the ITM 210 is pushed towards the doctor 2014, for example by air pressure (not shown). Alternatively, the force pushing the ITM 210 toward the doctor 2014 may be a backing roller 1141, such as a compressible (e.g., sponge) roller, in some embodiments, pressed down on the upper side or opposite side of the web by its own weight or by its spring action. As another alternative, the doctor 2014 may itself be pushed towards the ITM 210 while the latter is kept under tension.
The tip of the doctor blade 2014, which is comprised of a cylindrical smooth rod 2022, has a uniform radius across the width of the ITM 210 and its smoothness ensures laminar flow of liquid in the gap between it and the underside of the ITM 210. The nature of the flow may be similar to that of the liquid lubricant in the hydrodynamic bearing and reduces the liquid film 2030 (i.e., the surface of the 'lower run' of the ITM) that remains adhered to the underside of the ITM 210 to a certain thickness depending on the force pushing the ITM against the doctor blade 2014 and the radius of curvature of the rod 2022. Since both the radius and force are constant across the width of the web, the resulting film is uniform and its thickness can be set by appropriate selection of the applied force and the rod diameter. Excess liquid removed by doctor blade 2014 forms a small pool 2032 immediately upstream of rod 2022 before falling into tank 2016.
In an alternative embodiment of the invention, the surface of the ITM 210 to be coated with liquid may be facing up instead of down. In this case, rather than applying excess liquid to the ITM 210 (i.e., the 'lower run' surface of the ITM), liquid can be metered onto the surface to create and maintain a similarly small pool of liquid upstream of the line of contact between the wipe sheet and the upper surface of the web. In this case an air knife may be provided to prevent the treatment formulation (e.g., solution) from overflowing the side edges of the ITM 210 from the pool.
In embodiments of the invention, the pool 2032 provides a constant supply of treatment formulation (e.g., solution) across the width of the ITM 210, thereby allowing all areas of the ITM 210 to be coated even if liquid is repelled by portions of the surface of the web before reaching the doctor blade 2014 for any reason (e.g., due to 'beading').
The tank 2016 into which the remaining treatment formulation (e.g., solution) falls may be the primary reservoir from which liquid is pumped to coat the underside of the web with excess treatment formulation (e.g., solution), or it may be a separate tank that is drained into a main reservoir and/or emptied into a suitable disposal system.
The rod 2022 is made of a hard material such as fused silica to resist wear. Small particles of gravel or dust may be present in the liquid, which may damage the circular edges through which the liquid flows. Materials other than fused silica may be used, but should preferably have a brinell hardness in excess of 100 (e.g., in excess of 200, or in excess of 500, or even in excess of 1000). In embodiments of the invention, the material should be capable of forming smooth rods having a uniform diameter and a surface roughness of less than 10 microns, particularly less than 0.5 microns.
The rod 2022, which may have a radius of 6mm but may be only 0.5mm, is relatively fragile and may require a rod 2020 for support. To hold the rod 2022 precisely in place, a rod is formed with a groove 24, the rod 2022 resting in the groove 24. The rod may be retained in the recess 24 in any suitable manner. For example, an adhesive may be used and a rod 2020 may be used to press the rod 2022 against a flat surface such as a glass sheet until the adhesive sets. As a further alternative, the groove may be precisely machined to be slightly narrower than the stem diameter, and heat shrinkage may be used to hold the stem in place within the groove.
Sometimes, when certain formulations (e.g., solutions) are applied using such a doctor blade, a deposit 34 of solute accumulates on the downstream side of the doctor blade 2014. While not wishing to be bound by theory, it is believed that this may be caused by the immobilized membrane of the formulation (e.g., solution) adhering to the downstream side of the doctor blade and leaving behind the solute as it dries. Regardless of the cause of such deposit formation and its composition, if overgrowth is allowed, it ultimately interferes with the layer of treatment formulation (e.g., solution) applied to the ITM 210.
Embodiments of the present invention relate to an apparatus and method for replacing a doctor 2014 when the doctor becomes dirty. Fig. 4B shows an embodiment of how the doctor blade can be easily replaced and preferably without interrupting the web coating process or requiring a printing system to apply conditioning agent to its ITM.
In fig. 4B, twelve blades 1122 are uniformly mounted in notches around the circumference of the cylindrical rotatable turret 1120. The axially extending doctor blade 1122 functions in the same manner as the doctor blade 1122 in fig. 4A, and the turret 1120 serves the same purpose as the bar holder 2020. Instead of using a rod of circular cross-section, the doctor blade 1122 is configured as a strip with smooth circular and polished edges. The strip with rounded edges of uniform radius of curvature may be made, for example, by flattening a rod of circular cross-section. Doctor blade 1122 may suitably be made of stainless steel, but other hard materials that are resistant to wear may alternatively be used.
The manner in which turret 1120 and doctor blade 122 interact with ITM 110 is shown in fig. 5, with fig. 5 showing one embodiment of cleaning station 258 and treatment station 260 (e.g., for applying a layer of wet treatment formulation-e.g., as in step S209 of fig. 2 or step S101 of fig. 2).
In the embodiment of fig. 5, two separate cans 1125, 1127 are shown. An amount of the treatment solution (e.g., having one or more properties of step S205 of fig. 2 or step S95 of fig. 12) is stored in the tank 1125. For example, the treatment solution may be sprayed (i.e., by spraying apparatus 774) onto the surface of the ITM 210. Also shown in fig. 5 are brushes 1126A and 1126B for mechanically removing material from the surface of the ITM 210 to clean the ITM surface-for example, pressure may be applied between backing rolls 772A-772B disposed on opposing brushes 1126A-1126B, respectively.
In some embodiments, the material removed from the surface of the ITM comprises a dry treatment membrane, which may be dissolved, for example, in a liquid treatment formulation (e.g., having one or more properties in step S205 of fig. 2 or step S95 of fig. 12) stored in tank 1125—which may allow for recirculation of the treatment formulation. Thus, cleaning of the ITM surface can be affected by the treatment solution itself.
Irrespective of any mechanical properties of the system, in embodiments of the invention, the aqueous treatment formulation provided in step S205 of fig. 2 or step S95 of fig. 12 may be fully dissolvable (e.g., after drying, it may be fully dissolved in the aqueous treatment formulation).
The treatment formulation 1128 may be sprayed by a spraying device 1128. In the embodiment of fig. 5, one doctor blade 1122 is active-this is labeled 1122 Activity. A relatively thick layer of treatment formulation may be applied (e.g., by means 1128) and excess treatment formulation may be removed by the combination of doctor blade 1122 Activity and backing roll 1141, the backing roll 1141 being pushed against doctor blade 1122 Activity.
The spray apparatus 1128 is one example of an 'applicator' for applying a coating of a treatment formulation to the surface of the ITM 210. Another example of an applicator is a tank 2032, where the liquid contents of the tank remain on the ITM surface.
In general, the doctor blade 1122 Activity (or rounded tip thereof) and backing roller 1141 (or alternatively, the means for providing air pressure to the rounded tip 1122) are generally a coating thickness adjustment assembly-thus, in fig. 10A and 11A, the 'final thickness' of the treatment formulation can be adjusted according to the amount of force pushing the tip 1123 toward the opposite portion of the ITM 210 (e.g., toward the backing roller 1141), or vice versa.
In the embodiment of fig. 5, only one doctor blade 122 interacts with the ITM 110 at any given time, but when the blade becomes dirty, the turret 120 rotates to bring the next adjacent doctor blade into an operative position in which the blade is active, i.e., sufficiently close to the surface to remove excess liquid, and only allow a film of the desired thickness to adhere to the surface downstream of the apparatus.
Before returning to the operating position, at some later stage of the turret rotation cycle, the soiled blades 1122 pass through a cleaning device, such as a brush 1130, which removes any deposits and cleans the blades, after which the blades are again functional.
The rotation of the turret 1120 may be initiated by an operator as desired or may be performed at regular intervals.
The number of blades on the turret 1120 need not be twelve, but it is desirable that there be a sufficient number such that during conversion, as shown in fig. 8-9, there should be a time for two blades 1122 to function and interact with the ITM 110 at the same time. As a result, the blade is replaced substantially continuously, thereby not interrupting the film metering operation, which in turn allows the doctor blade to be changed without interrupting the printing system.
Fig. 8-9 are a more detailed perspective view and an exploded cross-sectional view of turret 1120 and blade cleaning brush 1130, respectively. Both mounted on a shaft rotatably supported in a metal frame 1140 in the immersion tank 1127. The shafts of the turret 1120 and the blade cleaning brush 1130 are connected to respective drive motors 1412 and 1144 mounted on the exterior of the can 1127. As can be seen in fig. 7, the turret 1120 is made of a hollow cylinder and its cylindrical surface may be perforated to reduce its weight and moment of inertia while still providing sufficient strength to support the doctor blade 1122.
While the blades 1122 supported by the turret 1120 have been shown as flat strips, it should be understood that they may alternatively be formed as circular bars as described with reference to fig. 4.
It has been found that for certain conditioning agents, vigorous agitation of the conditioning or treating agent solution can result in foam or foam formation. Ultrasonic waves may be used to break up the foam and such a de-bubbling device may be incorporated into the tank 1125.
As shown in fig. 10A and 10C, the doctor blade 1122 Activity can penetrate into the lower run of the ITM 210 as it is pushed against the backing roll 1141, or vice versa. As shown in fig. 10A, the ITM 210 (i.e., its lower stroke) is disposed between the roller 1141 and the doctor blade 1122 Activity. Thus, as the roller 1141 is pushed toward the doctor 1122 Activity, the roller 1141 pushes on the ITM 210 (i.e., its lower stroke) and the ITM 210 is pushed toward the doctor 1122 Activity -and vice versa.
In the embodiment of fig. 10A-10B, the central axis 1188 of the doctor blade 1122 Activity is shown. In fig. 10A-10B, the rounded tip of the doctor blade 1122 Activity is labeled 1123.
In the embodiment of fig. 10A, the tip 1123 faces the surface (i.e., local normal) of the ITM 210. In the embodiment of fig. 10A, the doctor blade 1122 Activity is oriented substantially normal to the partial surface of the ITM 210 facing the rounded tip 1123.
In the embodiment of fig. 10A, a downward force may be applied by roller 1141 toward rounded tip 1123 (i.e., via ITM). Alternatively, air pressure may be used to bias the ITM 210 toward the rounded tip 1123. This results in doctor blade 1122 Activity removing all but a thin liquid film (e.g., less than typically less than 1 micron) whose thickness is determined by the radius of curvature and the applied pressure.
All of the above may be equally applicable to the exemplary structure provided in fig. 10C. However, in the embodiment of fig. 10C, the backing roller has a compressible surface that is compressed when the rounded tips are pushed toward the ITM surface and/or vice versa (i.e., any configuration in which the backing roller and rounded tips are pushed toward each other), thereby causing the rounded tips to penetrate into the backing roller along with the ITM at a particular or desired penetration depth.
The spraying device 1128 or a bath in which the ITM surface may be immersed or any other device for applying the primer coating may be considered an 'applicator' for applying the ITM with a liquid treatment formulation. In addition, the combination of (i) the rounded surface 1123 (e.g., rounded tip) and (ii) the means for applying a reaction force (e.g., roller 1141) to urge the rounded surface 1112 in the opposite direction toward the ITM 210 (or vice versa) forms a thickness-adjusting assembly for removing excess liquid so as to leave only a desired uniform thin layer (e.g., sub-micron thickness) of the treatment formulation.
In embodiments of the invention, even though the rounded tip 1123 is in external contact with the opposing ITM surface (e.g., to maintain a gap therebetween, the applicator may still indirectly apply pressure to the ITM through the treatment fluid.
In some embodiments, the rounded tip applies a pressure of at least 0.1 bar, or at least 0.25 bar, or at least 0.35 bar, or at least 0.5 bar, and optionally, up to 2 bar, or up to 1.5 bar, or up to 1 bar.
The pressure may be positioned in the printing direction. For example, 'pressure strips' (e.g., strips may be elongated in the cross-printing direction) (e.g., having a length in the cross-printing direction of at least 10cm, at least 30cm, at least 50cm, at least 70cm, or at least 100cm, and typically at most 250cm, at most 200 cm, or at most 150 cm) may be applied to the ITM by an applicator such that (i) the maximum pressure of the ITM applied to the strip is a P strip maximum, having a value of at least 0.1 bar, or at least 0.25 bar, or at least 0.35 bar, or at least 0.5 bar, and optionally, at most 2 bar, or at most 1.5 bar, or at most 1 bar, (ii) the local pressure applied to the ITM by the applicator is at least 0.5 x P strip maximum at all locations within the strip, and (iii) all locations on opposite sides of the strip in the cross-shift from the strip upstream and downstream of the cross-strip by at most 2cm, or at most 1cm, or at most 5mm, or at most 3mm, at most 2.5 mm, at most 0.5mm, or at most 0.5 mm.
As shown in fig. 11A, the presence (e.g., remaining stationary) of a rounded tip 1123 (e.g., a spatula) may create a shear field or velocity gradient-see, e.g., fig. 11B and 11C. At a location on the ITM surface, the velocity of the treatment fluid may be non-zero (e.g., substantially equal to the velocity of the ITM) due to the non-stick boundary condition with the ITM surface, and at the applicator, the velocity of the treatment fluid may be zero.
In some embodiments, i.e., in step S209 of fig. 2 or step S101 of fig. 12, the forming of the thin wet-treated layer includes generating a velocity gradient of the aqueous treatment solution (e.g., in a direction normal to the ITM surface) at a strong velocity gradient IVG location x=xIVG Position of, the location (i) generally being displaced from (e.g., up to 3 microns, or up to 2 microns, or up to 1 micron) and/or between the applicator and the stripping surface of the applicator, and ii.e., at the IVG location, the magnitude of the velocity gradient is equal to or exceeds a VG value of at least 106sec-1, or at least 2×106sec-1, or at least 4×106sec-1, or at least 5×106sec-1, or at least 7.5×106sec-1, or at least 107sec-1, or at least 2×107sec-1, or at least 4×107sec-1, or at least 5×107sec-1, or at least 7.5×107sec-1.
In some embodiments, the velocity gradient is positioned along the printing direction such that:
i. At an upstream location upstream of the IVG location, the maximum velocity gradient is at most x% of the velocity gradient value at the IVG location;
At a downstream location downstream of the IVG location, a maximum velocity gradient of at most x% of the velocity gradient value at the IVG location;
X has a value of at most 50, or at most 30, or at most 20, or at most 10, and/or
The upstream and downstream positions are each shifted from the IVG position by at most 2cm, or at most 1.5cm, or at most 1.25cm, or at most 1cm, or at most 9mm, or at most 8 mm, or at most 7.5mm, or at most 7mm, or at most 6mm, or at most 5mm.
In some embodiments, the rounded surface is urged toward the ITM in the cross-printing direction with a force density of at least 250g/cm, or at least 350g/cm, or at least 400gm/cm, and/or up to 1kg/cm, or up to 750 g/cm, or up to 600g/cm, or vice versa.
Discussion of FIG. 12
Embodiments of the present invention relate to the printing process depicted in fig. 12. In some non-limiting embodiments, the apparatus, systems, and devices described in fig. 3-11 may be employed to perform the method of fig. 12. The order of steps in fig. 12 is not limiting-in particular, steps S91-S99 may be performed in any order. In some embodiments, steps S101-S117 are performed in the order shown in fig. 12.
In some embodiments, step S91 may be performed to provide any feature or combination of features of step S201 of fig. 2.
In some embodiments, step S95 may be performed to provide any feature or combination of features of step S205 of fig. 2.
In some embodiments, step S101 may be performed to provide any feature or combination of features of step S209 of fig. 2.
In some embodiments, step S105 may be performed to provide any feature or combination of features of step S213 of fig. 2.
In some embodiments, step S109 may be performed to provide any feature or combination of features of step S217 of fig. 2.
In some embodiments, step S113 may be performed to provide any feature or combination of features of step S221 of fig. 2.
In some embodiments, step S117 may be performed to provide any feature or combination of features of step S225 of fig. 2.
Steps S91-99 relate to the ingredients or components or consumables used in the process of fig. 12, while steps S101-S117 relate to the process itself. Briefly, (i) in step S101, a thin treatment layer of the wet treatment formulation is applied to an Intermediate Transfer Member (ITM) (e.g., a release layer having hydrophobic properties), (ii) in step S105, such treatment layer is dried (e.g., flash dried) to a thin dried treatment film on the release surface of the ITM, (iii) in step S109, droplets of aqueous ink are deposited (e.g., by jetting) onto the thin dried treatment film, (iv) in step S113, the ink image is dried to leave an ink image on the dried treatment film on the ITM, and (v) in step S117, the ink image is transferred onto a print substrate (e.g., together with the dried treatment film).
Details of the components of steps S91-S99 and process steps S101-S117 are described below.
In an embodiment of the present invention, steps S91 to S117 are performed as follows:
(A) In step S91, ITM-e.g., at most moderately hydrophobic and/or having hydrophobic properties and/or having a silicone-based release layer and/or only moderately hydrophobic and/or lacking functional groups is provided;
(B) In step S95, an aqueous treatment solution is provided (e.g., (i) having a low evaporation load, and/or (ii) being surfactant-rich, and/or (ii) having only moderately hydrophilic, and/or (iii) comprising a water-soluble polymer, and/or (iv) comprising a quaternary ammonium salt, and/or (v) having a viscosity low enough that the solution can spread into a uniform thin layer, and/or (vi) comprising a hygroscopic material, and/or (vii) being substantially free of organic solvent, and/or (viii) having a concentration of flocculant containing multivalent cations up to low;
(C) In step S99, an aqueous ink is provided;
(D) In step S101, an aqueous treatment formulation is applied to the release surface of the ITM (e.g., in-service ITM) to form a thin wet-treated layer (e.g., thickness. Ltoreq.0.8 μ) thereon;
(E) In step S105, the wet thin treated layer is subjected to a drying treatment (e.g., flash drying) on the ITM release surface to leave a thin dried treated film (e.g., thickness. Ltoreq.0.08 μ) of water-soluble polymer on the ITM release surface. For example, the thin dry treated film may have one or both of (i) for example, the treated film is a continuous and/or cohesive film, (ii) the upper surface of the dry treated film is characterized by a very low roughness;
(F) In step S109, aqueous ink droplets are deposited (e.g., by inkjet) onto the thin drying process film to form an ink image thereon;
(G) In step S119, the ink image leaves an ink residue on the drying treatment film (e.g., to achieve good dot spread)
(H) In step S119, the dried ink image (e.g., at a relatively low temperature) (e.g., along with the drying process film) is transferred from the ITM surface to a print substrate (e.g., paper-based or plastic-based).
In some embodiments, the process of fig. 12 is performed such that little or no beading occurs when the aqueous treatment solution is applied to the ITM in step S101, thereby making the resulting thin dry treatment film (i.e., obtained in step S105) continuous and/or having a smooth (e.g., extremely smooth) upper surface. The smooth upper surface may be important to obtain high quality substrate resident ink images.
One feature associated with conventional methods of pre-treating the ITM and applying the ink image on top of the pre-treated ITM is that after transfer to the substrate, the dried treatment formulation (e.g., after drying) resides on top of the ink image and may add undesirable gloss to the ink image. To overcome or minimize this potential undesirable effect, a thin dry-treated film (e.g., having a thickness of at most 400 nanometers, or at most 200 nanometers, or at most 100 nanometers, or even less) is obtained in step S105. In addition, in some embodiments, such a thin drying treatment film (i.e., obtained in step S105) is continuous, which may be beneficial, as discussed below.
Although not limiting, in some embodiments, the process of fig. 12 is performed such that the image transfer of step S117 is performed at a low temperature (e.g., for an uncoated substrate) -e.g., at a temperature of at most 90 ℃, or at most 85 ℃, at most 80 ℃, or at most 75 ℃, at most 70 ℃, or at most 65 ℃, at most 60 ℃ -e.g., at about 60 ℃.
Discussion of step S91 of FIG. 12
In various embodiments, the ITM (i.e., the ITM provided in step S91 of fig. 12 or in step S201 of fig. 2) may provide one or more (i.e., any combination) of the following features A1-A5:
A1. in some embodiments, the release layer is formed of a silicone material (e.g., addition cure) -this provides the ITM with a hydrophobic property useful in step S117;
A2 before use in the method of FIG. 12, the silicone-based release layer has been created in a manner that reduces its hydrophobicity. For example, rather than relying on the addition of functional reactive groups to render the release layer hydrophilic, the silicone release layer may be cured such that polar atoms in the polar groups (e.g., oxygen atoms in the polar Si-O-Si moieties) are aligned or otherwise face outward relative to the release layer surface. In this embodiment, in step S117, the oxygen atoms of "Si-O-Si" are not chemically bonded to the materials in the processing solution, the dried ink image, and/or the dried processing film under typical process conditions. However, in steps S101-S105, the hydrophilicity of the outwardly facing polarity "O" may benefit.
A3 the release surface of the ITM can have moderately hydrophobic properties, but not excessively hydrophobic. Thus, the release surface may have a surface energy (at 25 ℃) of at least 23 dynes/cm, and more typically at least 25 dynes/cm, at least 28 dynes/cm, at least 30 dynes/cm, at least 32 dynes/cm, at least 34 dynes/cm, or at least 36 dynes/cm, and/or at most 48 dynes/cm, at most 46 dynes/cm, at most 44 dynes/cm, at most 42 dynes/cm, at most 40 dynes/cm, at most 38 dynes/cm, or at most 37 dynes/cm.
A4 the receding contact angle of the distilled water drop on the ink receiving or release layer surface is typically at least 30 °, and more typically, 30 ° to 75 °,30 ° to 65 °,30 ° to 55 °, or 35 ° to 55 °;
A5 the release layer of the ITM may be free or substantially free of functional groups bonded within the crosslinked polymer structure, which the inventors believe may increase or promote undesirable adhesion.
Discussion of step S95 of FIG. 12
In step S95, an aqueous treatment formulation is provided. Such treatment formulations comprise at least 50 wt%, or at least 55 wt%, or at least 60 wt%, or at least 65 wt% of an aqueous carrier liquid).
In various embodiments, the aqueous treatment formulation (i.e., the aqueous treatment formulation in its initial state prior to the application of step S101 of fig. 12 or the aqueous treatment formulation in its initial state prior to the application of step S205 of fig. 1) may provide one or more (i.e., any combination) of the following features:
B1. Low evaporation load—in some embodiments, the initial aqueous treatment formulation has a low evaporation load and is relatively rich in materials that are solid at 60 ℃ (and at atmospheric pressure). As will be discussed below, in some embodiments this may be useful, thereby allowing the viscosity to increase rapidly during step S105 in a very short time, thereby counteracting any tendency of the aqueous treatment formulation to bead up on the release surface of the ITM, which release surface has a hydrophobic character. For example, the 60 ℃ evaporation load may be at most 10:1, or at most 9:1, or at most 8:1, or at most 6:1, or at most 5:1, or at most 4:1. In some embodiments, this is useful for obtaining a continuous dry treatment film lacking bald mass.
B2. Surfactant-rich-in some embodiments, the initial aqueous treatment formulation comprises at least 2 wt%, or at least 2.5 wt%, at least 3 wt%, or at least 4 wt%, or at least 5 wt%, or at least 6 wt%, or at least 7 wt%, or at least 8 wt%, or at least 9 wt%, or at least 10 wt% of one or more surfactants. For example, one or more surfactants present in the initial aqueous treatment formulation (e.g., at least 50 wt%, or at least 75 wt%, or at least 90 wt% of the surfactant in the treatment formulation) may be solid at 60 ℃, thus contributing to a low evaporation load. In some embodiments, a relatively higher concentration of surfactant in the initial aqueous treatment formulation may be used to make the aqueous treatment formulation less hydrophilic, thereby reducing the tendency of the aqueous treatment formulation to bead up on the release surface of the ITM in steps S101 and/or S105. In some embodiments, because the surfactant is a wetting agent, a relatively high concentration of surfactant may be used to spread the aqueous ink droplets (or counteract any tendency of the ink droplets to shrink) on the surface of the dried ink film during steps S109 and/or S113, thereby increasing the coverage of the resulting ink dots that ultimately reside on the substrate.
B3. Quaternary ammonium salts are present (e.g., at relatively high concentrations) -in some embodiments, the initial aqueous treatment formulation comprises at least 1.5 wt% (e.g., at least 2 wt%, at least 2.5 wt%, at least 3 wt%, at least 4 wt%, at least 5 wt%) quaternary ammonium salt. In some embodiments, the solubility of the quaternary ammonium salt in water is at least 5% at 25 ℃. In some embodiments, the ammonium quaternary ammonium salt contains aliphatic substituents.
B4. Moderately hydrophilic initial aqueous treatment formulations-in some embodiments, the initial aqueous treatment formulation has only moderately hydrophilic-for example, a static surface tension at 25 ℃ of at most 32 dynes/cm (e.g., between 20 dynes/cm and 32 dynes/cm), or at most 30 dynes/cm (e.g., between 20 dynes/cm and 32 dynes/cm), or at most 28 dynes/cm (e.g., between 20 dynes/cm and 32 dynes/cm). Because the exfoliated surface of the ITM has moderately hydrophobic (or moderately hydrophilic) properties, it may not be useful to employ an initial aqueous treatment formulation having a high hydrophilicity, which would result in the aqueous treatment formulation beading on the surface of the ITM in steps S101 and/or S105. This may be particularly important in the case of a thin wet treated layer thickness, and it is desirable to avoid bald spots, so the resulting thin dry treated film is continuous.
B5. There is a water-soluble polymer that forms the polymer matrix (e.g., after drying in step S105 of fig. 21 or after drying in step S213 of fig. 2) -in some embodiments, the initial aqueous formulation comprises at least 1.5 wt% (e.g., at least 2 wt%, at least 2.5 wt%, or at least 3 wt%) of at least one water-soluble polymer, more particularly a matrix-forming polymer, that has a solubility in water of at least 5% at 25 ℃. The one or more polymers include, but are not limited to, polyvinyl alcohol (PVA), water-soluble cellulose, including derivatives thereof, such as hydroxypropyl methylcellulose, PVP, polyethylene oxide, and acrylic. In some embodiments, even when the dried film is relatively thin, the formation of the polymer matrix facilitates the formation of the film and/or imparts a desired elasticity and/or cohesiveness or tensile strength to the dried film.
B6. the inventors have found that it is desirable to apply a thin but relatively uniform layer of the wet aqueous treatment formulation in step S101 of fig. 12 (or in step S209 of fig. 2) before application to the ITM in step S101 of fig. 12 (or before application to the ITM in step S209 of fig. 2) at a relatively low viscosity, as will be discussed below. To this end, the 25 ℃ dynamic viscosity of the initial aqueous treatment formulation may be at most 100cP, or at most 80cP, or at most 40cP, or at most 30cP. Alternatively or additionally, the 25 ℃ dynamic viscosity of the initial aqueous treatment formulation may be at least 8cP, or at least 10cP, or at least 12cP, or at least 14 cP-e.g., in the range of 8cP to 100cP, 10cP to 100cP, 12cP to 100cP, 14cP to 100cP, 10cP to 60cP, or 12cP to 40 cP.
In some embodiments, this feature may be particularly useful when the treatment formulation is applied to the ITM, as the ITM moves at high speed (e.g., through an applicator configuration-e.g., a stationary applicator configuration).
B7. the absence of an organic solvent such as glycerol-in some embodiments, the presence of a low vapor pressure organic solvent may delay the drying of the treatment formulation on the ITM surface in step S105 and/or produce a treatment film lacking the desired elasticity and/or cohesiveness or tensile strength desired for transfer step S117. In some embodiments, the formulation is free of organic solvents, regardless of its vapor pressure in the pure state, and/or comprises up to 3 wt%, up to 2 wt%, up to 1 wt%, or up to 0.5 wt%, or up to 0.25 wt%, or up to 0.1 wt% of organic solvents. In particular, in some embodiments, the formulation is free of organic solvents and/or comprises up to 3 wt%, up to 2 wt%, up to 1 wt%, or up to 0.5 wt%, or up to 0.25 wt%, or up to 0.1 wt% glycerol. In some embodiments, the formulation is completely free of glycerol.
B8. Comprising a water absorbing material-in some embodiments, the initial aqueous treatment formulation comprises a solid water absorbing agent selected to absorb water from the ink when the water absorbing agent is disposed within the solid drying treatment film. For example, such a solid water absorbing agent may have a melting point (i.e. when in pure state) of at most 60 ℃, or at most 50 ℃, or at most 40 ℃, or at most 30 ℃, or at most 25 ℃ -for example, at least 1.5 wt%, or at least 2 wt%, or at least 2.5 wt%, or at least 3 wt%. Examples of such water absorbing agents include, but are not limited to, sucrose, urea, sorbitol, and isomalt.
B9. There are multiple types of surfactants, including at least one surfactant with a surface tension exceeding that of the overall formulation-in some embodiments, the initial aqueous treatment formulation comprises a first surfactant and a second surfactant, wherein the first surfactant is more hydrophobic (and has a lower surface tension) than the second surfactant (e.g., quaternary ammonium salt). In one embodiment, the first surfactant comprises a silicone polyether and/or the second surfactant is a quaternary ammonium salt. For example, the absolute value of the respective surface tension difference between the first surfactant and the second surfactant may be at least 5 dynes/cm, or at least 7.5 dynes/cm, or at least 10 dynes/cm. For example, (i) the surface tension of the first surfactant is less than the surface tension of the initial aqueous treatment formulation (e.g., at least 1 dyne/cm, or at least 2 dyne/cm, or at least 3 dyne/cm, or at least 4 dyne/cm, or at least 5 dyne/cm, or at least 7 dyne/cm) and/or (ii) the surface tension of the second surfactant exceeds the surface tension of the initial aqueous treatment formulation (e.g., at least 1 dyne/cm, or at least 2 dyne/cm, or at least 3 dyne/cm, or at least 4 dyne/cm, or at least 5 dyne/cm, or at least 7 dyne/cm).
In some embodiments, the primary purpose of the first surfactant is to reduce the hydrophilicity of the initial aqueous treatment formulation (e.g., the values described above in 'feature A4') -for example, thus, the treatment formulation does not bead up in steps S101 and/or S105. Alternatively or additionally, the primary purpose of the second surfactant is to provide any of the features described in B3 above.
In various embodiments, the initial aqueous treatment formulation comprises at least 2 wt%, or at least 2.5 wt%, or at least 3 wt%, or at least 4 wt%, or at least 5 wt% of the first surfactant and/or at least 2 wt%, or at least 2.5 wt%, or at least 3 wt%, or at least 4 wt%, or at least 5 wt% of the second surfactant. For example, the ratio between the weight concentration of the first surfactant and the weight concentration of the second surfactant is at least 0.1, or at least 0.2, or 0.25, or at least 0.33, or at least 0.5, or at least 0.75 and/or at most 10, or at most 4, or at most 3, at most 2, or at most 4/3.
B10. flocculants having up to low concentrations of multivalent cations (such as calcium chloride) -in some embodiments, these compounds are believed to be detrimental to image quality.
Discussion of step S99 of FIG. 12
Potential characteristics of aqueous inks:
Features C1-in some embodiments (e.g., involving the methods of fig. 2 or 12), the ink provides one or more features (any combination of features) disclosed in PCT/IB13/51755 or US2015/0025179, PCT/IB14/02395, or US 14/917561, all of which are incorporated herein by reference.
Discussion of step S105 of FIG. 12
Feature D1-the drying treatment layer formed in step S105 is thin, but not a monolayer (e.g., significantly thicker than a monolayer) -e.g., has a thickness of at most 100 nanometers. In some embodiments, the drying treatment layer is extremely thin, having a thickness of at most 80 nanometers, or at most 75 nanometers, or at most 70 nanometers, or at most 65 nanometers, or at most 60 nanometers, or at most 55 nanometers, or at most 50 nanometers. However, in various embodiments, even if the drying treatment film is extremely thin, it is thicker than a single layer or a single layer structure. Thus, in various embodiments, the thickness of the drying treatment layer may be at least 20 nanometers, or at least 30 nanometers, or at least 40 nanometers, or at least 50 nanometers. In some embodiments, providing such a 'bulk' (i.e., a minimum thickness feature-e.g., in conjunction with one or more other features described below) facilitates forming a drying treatment film having cohesiveness and/or elasticity-which can be used in step S117, wherein it is desirable for the drying treatment film (i.e., at that stage, carrying a dried ink image thereon) to maintain its structural integrity when transferred from the ITM to the substrate.
In some embodiments, the dried treatment formulation may add undesirable gloss to the resulting ink image after transfer to the substrate-thus, the ability to form a thin but cohesive dried treatment layer may be useful. The thin layer also helps to evaporate and dry the layer into a film.
The feature D2-the drying treatment film formed on the ITM in step S105 is continuous and has no 'bald block' thereon, although it is thin or extremely thin. As will be discussed below, in some embodiments, to achieve this (i.e., particularly for thin or very thin layers), it may be desirable to both (i) the initially applied wet layer applied in step S101 is continuous and free of bald blocks, even if the initially applied wet layer is relatively thin, with a thickness of at most about 1 μ (or at most 0.8 μ, or at most 0.6 μ, or at most 0.4 μ, and more typically at most 0.3 μ, at most 0.25 μ, or at most 0.2 μ, and/or at least 0.1 μ), and (ii) the drying process of step S105 occurs very rapidly, wherein the viscosity of the drying process formulation increases very rapidly (e.g., within at most 100 milliseconds, within at most 50 milliseconds, within at most 40 milliseconds, within at most 30 milliseconds, within at most 25 milliseconds, within at most 20 milliseconds, within at most 15 milliseconds, or at least 100, or at least 1000, or at least 10,000 times). Because the ITM release layer has hydrophobic properties and the treatment formulation is aqueous and more hydrophilic, the aqueous treatment formulation can undergo beading when applied to the ITM release layer. However, if the viscosity increases rapidly after application of the wet treatment layer, the higher viscosity treatment formulation may resist beading better than the low viscosity formulation. In some embodiments and as discussed above in feature "B1", the aqueous treatment formulation may be enriched in solids and/or include a low evaporation load-which may facilitate a rapid increase in viscosity.
Another anti-beading feature that can be used to obtain a continuous dry treatment film (i.e., the anti-beading of the treatment formulation in steps S101-S105) can involve the relative properties of (i) the release surface of the ITM, which in some embodiments has hydrophobic properties but is not excessively hydrophobic (see feature "BA"); (ii) the aqueous treatment formulation, which in some embodiments has hydrophilic properties but is not excessively hydrophilic (see feature "B4"). The driving force for beading can be small when the static surface tension between the aqueous treatment formulation and the release layer of the ITM can be relatively small, and the viscosity of the aqueous treatment formation (e.g., when it increases rapidly) can be sufficient to prevent beading.
As discussed above, although the ITM release layer has only moderate hydrophobicity (see feature "A3"), the ITM release layer may have specific properties (see feature "A5"), which limit the adhesion between the ITM release layer and the dried treatment film-thus, even if the treatment surface has only moderate hydrophobicity to avoid the treatment formulation beading thereon in steps S101 and/or S105, it may (e.g., due at least in part to feature "B2") avoid paying a 'cost' for the benefit in step S117 when it is desired to minimize adhesion between the ITM release layer and the dried treatment film later.
In some embodiments, this can be used to generate a substrate resident ink image with suitable image integrity (see, e.g., fig. 15A-15D).
The feature d3. The dried treated film formed on the ITM in step S105 is characterized by an extremely low surface roughness-in some embodiments, the surface roughness may be characterized by a roughness average Ra (a commonly used one-dimensional roughness parameter) of at most 20 nm, or at most 18 nm, or at most 16 nm, or at most 15 nm, or at most 14 nm, or at most 12 nm, or at most 10 nm, or at most 9 nm, or at most 8 nm, or at most 7 nm, or at most 6 nm. The dried processed film formed on the ITM can have an Ra of at least 3 nanometers or at least 5 nanometers.
In some embodiments, such a low roughness average Ra -for example, even when the ratio between the roughness average Ra and the thickness of the dried treatment layer is at least 0.02, or at least 0.03, or at least 0.04, or at least 0.05, or at least 0.06, or at least 0.07, or at least 0.08, or at least 0.9, or at least 0.1, or at least 0.11, or at least 0.12, or at least 0.13, or at least 0.14, or at least 0.15, or at least 0.16, or at least 0.17, or at least 0.18, or at least 0.19, or at least 0.2-can be achieved even for thin or very thin dried treatment films formed in step S105.
In some embodiments, the dried treated film on which the aqueous ink droplets are deposited and the surface (e.g., upper surface) of the dried treated film are characterized by a dimensionless ratio between (i) the average roughness Ra and (ii) the thickness of the dried treated layer, wherein the dimensionless ratio is at most 0.5, at most 0.4, at most 0.3, at most 0.25, at most 0.2, at most 0.15, or at most 0.1, and optionally, at least 0.02, or at least 0.03, or at least 0.04, or at least 0.05, or at least 0.06, or at least 0.07, or at least 0.08.
Feature D4-in some embodiments, a continuous dry film covering an entire rectangle of at least 10cm x 1m, or 1m2, 3m2, or 10m2 overall, may be obtained. The film may have a thickness or average thickness of at most 120nm, at most 100nm, at most 80nm, at most 60nm, at most 50nm, or at most 40nm, and typically at least 20nm, at least 25nm, or at least 30 nm.
Discussion of steps S109-S117
In various embodiments, steps S109 and/or S113 and/or S117 may be performed to provide one or more of the following process-related features:
Feature E1 in some embodiments, step S117 is performed at a low transfer temperature (e.g., up to 90 ℃, or 80 ℃, or 75 ℃, or 70 ℃, or 65 ℃, or 60 ℃ -due to thermoplastic properties and/or tensile strength), even when the image is transferred to an uncoated substrate. In some embodiments, providing a low temperature transfer step may be used to reduce or avoid clogging of the inkjet head and/or may also be used to make the printing process overall more environmentally friendly.
In some embodiments, both the dried processing film and the dried ink image are tacky at the transfer temperature and therefore can be cleanly peeled from the release layer even at relatively low temperatures. The property may be due at least in part to the chemical nature of the initial aqueous treatment solution. In some embodiments, the chemistry and structure of the release layer (see, e.g., feature 'A5') may also be used to provide a low temperature transfer process in step S117.
The feature E2-spreading-the way the droplets are deposited on the film (e.g. wetting angle) and the physical and/or chemical properties of the treated film [ nano-particles in A2 and/or A3 and/or A8-ink may also contribute ] is such that upon impact drying the treated film the radius of the ink dots immediately exceeds the radius of the precursor liquid droplets-e.g. the size of each droplet increases to exceed the size resulting from the spreading of the droplets caused by the impact energy of the droplets. [ Dmaximum=2 the maximum value of R, or D impact maximum = 2·r impact maximum ].
Fig. 13A-13E schematically depict the deposition of ink droplets on an ITM (e.g., its release surface). In fig. 13A, the ink droplets move toward the ITM. Fig. 13B-13C depict ink droplets immediately after collision between (i) a droplet and (ii) an ITM (or a dried processing film thereon). The kinetic energy of the droplets causes deformation of the droplets-this is shown in fig. 13B-13C. In particular, the kinetic energy of the droplet causes the droplet to expand outwardly- -FIG. 13C shows that the maximum radius of the droplet at impact- -i.e., the maximum increase in radius, is due to deformation caused by the kinetic energy of the droplet. After the drop reaches the maximum radius ("R at impact" or "rlax at impact" is used interchangeably), for example, within 10 milliseconds of impact, the drop (or its subsequent point because each drop eventually becomes a dot after drying-first the point resides on the ITM (e.g., by drying the processing film), as shown in fig. 13D, and after transfer, the drop resides on the substrate, as shown in fig. 13E) due to the kinetic-driven drop deformation. The droplet or its subsequent point may be further expanded due to physicochemical forces or chemical interactions. This is a spreading phenomenon schematically illustrated by comparing fig. 13C or 13D with fig. 13B. Again, note that 13A-13E are schematic and that droplets that do not require deformation will have the particular shape shown in fig. 13A-13E.
14A-14B provide a topographical map of a instrumented plot of a dried processing film produced in accordance with an embodiment of the present invention.
General comments regarding fig. 2 and 12-in some embodiments, step S201 of fig. 2 may be performed to provide any feature or combination of features of step S91 of fig. 12. In some embodiments, step S205 of fig. 2 may be performed to provide any feature or combination of features of step S95 of fig. 12. In some embodiments, step S209 of fig. 2 may be performed to provide any feature or combination of features of step S101 of fig. 12. In some embodiments, step S213 of fig. 2 may be performed to provide any feature or combination of features of step S105 of fig. 12. In some embodiments, step S217 of fig. 2 may be performed to provide any feature or combination of features of step S109 of fig. 12. In some embodiments, step S221 of fig. 2 may be performed to provide any feature or combination of features of step S113 of fig. 12. In some embodiments, step S225 of fig. 2 may be performed to provide any feature or combination of features of step S117 of fig. 12.
14A-14B provide an instrumental map of the topography of a dried continuous processing film produced according to some embodiments of the invention. The topographical features generated by the Zygo laser interferometer show average film thicknesses of about 40-50 nanometers (fig. 14A) and about 100 nanometers (fig. 14B), respectively. The film surface was extremely smooth, exhibiting an average roughness (Ra) of about 7 nm in fig. 14A, and a slightly smaller average roughness (Ra) in fig. 14B. In other topographical maps, an average film thickness of about 40 nanometers and an Ra of about 5 nanometers were observed.
Although the film is thin (typically at most 120nm, at most 100nm, at most 80nm, at most 70nm, at most 60nm, at most 50nm, or at most 40nm, more typically 30nm to 100nm, 40nm to 100nm, 40nm to 80nm, 40nm to 70nm, or 40nm to 60 nm), the film is typically free of bare spots and defect-free, even over a large area of 20cm2、50cm2 or 200cm2 or more.
Without wishing to be bound by theory, the inventors believe that the ultra-smooth surface of the dry-treated film enables spreading of the ink dots to occur in a uniform and controlled manner, thereby enabling the formation of unfavorable streams and the like to be significantly reduced or avoided. The shape of the resulting dots is very similar in quality to the excellent shapes (convexity, roundness, edge definition) obtained in application number PCT/IB2013/000840 of Landa Corporation, which is incorporated by reference for all purposes as if fully set forth herein. This is particularly surprising in view of the spreading mechanism utilized by the present disclosure, as compared to the surface tension controlled droplet pinning and shrinking disclosed in the application.
Fig. 15A-15D illustrate some examples of ink dots on a paper substrate. In particular, FIG. 15A provides a top view of a magnified image of a single dot of ink that adheres to a coated paper substrate (130 GSM) after being ejected onto and transferred from an ITM in accordance with an embodiment of the present invention, FIG. 15B provides a top view of a magnified image of a plurality of ink-ejection dots disposed within a field of view on a coated paper substrate (130 GSM) in accordance with an embodiment of the present invention, FIG. 15C provides a top view of a magnified image of a single dot of ink that adheres to an uncoated paper substrate after being ejected onto and transferred from an ITM in accordance with an embodiment of the present invention, and FIG. 15D provides a top view of a magnified image of a plurality of ink-ejection dots disposed within a field of view on an uncoated paper substrate in accordance with an embodiment of the present invention.
Point and convexity measurements were performed according to the procedure disclosed in PCT/IB 2013/000840. Further, point and convexity measurements are performed essentially as follows:
image acquisition method
Acquisition of the dot images was performed using a LEXT (Olympus) OLS3000 microscopy. The image is taken with X100 and X20 optical zoom. The color image is saved in uncompressed format (Tiff) with a resolution of 640x640 pixels.
In addition, in order to measure the dot thickness and diameter, ZYGO micromirrors with X100 lenses were used.
With respect to analysis
The basic parameters (and units) included in this work are:
diameter-fit ring [ D point ] [ mic ]
Perimeter [ P ] [ mic ]
Area measured [ A ] [ pix 2]
Minimum convex area [ CSA ] [ pix 2]
Optical uniformity [ STD ] [8bit order modulation ]
Thickness [ H point ] [ mic ]
From these parameters, the following is calculated:
Aspect ratio, R aspect=D/H points [ dimensionless ]
Point circularity ER=P2/(4pi.A) [ dimensionless ]
DR Point ER-1 [ dimensionless ]
Convexity CX=AA/CSA [ dimensionless ]
Non convexity: dc Point=1-CX [ dimensionless ]
The analysis was performed using MATLAB image processing tools, using the above described analysis procedure applied in WO2013/132418, where possible.
Blanket
ITM can be manufactured in the inventive manner described in fig. 17-22 and the description associated therewith. Such ITM may be particularly suitable for the Nanographic PrintingTM technique of Landa Corporation.
Referring now to fig. 16, fig. 16 schematically shows a cross section through the carrier 10. In all the figures, the carrier 10 is shown as a solid black line in order to distinguish it from the layers forming part of the finished product. The carrier 10 has a carrier contact surface 12.
In some embodiments, the carrier contact surface 12 may be a well polished planar surface having a roughness (Ra) of at most about 50nm, at most 30nm, at most 20m, at most 15nm, at most 12nm, or more typically, at most 10nm, at most 7nm, or at most 5 nm. In some embodiments, the carrier contact surface 12 may be between 1nm and 50nm, between 3nm and 25nm, between 3nm and 20nm, or between 5nm and 20 nm.
The hydrophilic nature of the carrier contact surface 12 is described below.
In some embodiments, the carrier 10 may be inflexible, e.g., formed from a glass sheet or a thick metal sheet.
In some embodiments, the carrier 10 may advantageously be formed of a flexible foil, such as a flexible foil consisting essentially of or comprising aluminum, nickel, and/or chromium. In one embodiment, the foil is an aluminized PET (polyethylene terephthalate, polyester) sheet, such as PET coated with pyrolytic aluminum metal. The top coating of aluminum may be protected by a polymer coating, the sheet typically having a thickness of between 0.05mm and 1.00mm in order to maintain flexibility but difficult to bend through small radii to avoid wrinkling.
In some embodiments, the carrier 10 may advantageously be formed from an antistatic polymer film, such as a polyester film, such as PET. The antistatic properties of the antistatic film can be achieved by various means known to those skilled in the art, including the addition of various additives (such as ammonium salts) to the polymer composition.
In one step of the ITM manufacturing process of the present invention, the result of which is shown in fig. 17, a fluid first curable composition (shown as 36 in fig. 24B) is provided and a layer 16 is formed therefrom on the carrier contact surface 12, the layer 16 constituting an initial peel ply having the outer ink transfer surface 14.
The fluid first curable composition of layer 16 may comprise an elastomer, typically made of a silicone polymer, such as a polydimethylsiloxane, e.g., a vinyl-terminated polydimethylsiloxane.
In some embodiments, the fluid first curable material includes a vinyl-functional silicone polymer, such as a vinyl-silicone polymer that includes at least one pendant vinyl group in addition to a terminal vinyl group, such as a vinyl-functional polydimethylsiloxane.
In some exemplary embodiments, the fluid first curable material includes a vinyl terminated polydimethylsiloxane, a vinyl functional polydimethylsiloxane that includes at least one pendant vinyl group on the polysiloxane chain in addition to the terminal vinyl groups, a cross-linking agent, and an addition cure catalyst, and optionally further includes a cure retarder.
The curable adhesive composition may comprise any suitable amount of an addition cure catalyst, typically up to 0.01% prepolymer per mole, as is known in the art.
Exemplary formulations for the fluid first curable material are provided below in the examples.
A layer 16 of the fluid first curable composition is applied to the carrier contact surface 12 and subsequently cured. The layer 16 may be spread to a desired thickness using, for example, a doctor blade (knife on a roll) without allowing the doctor blade to contact the surface of the ink transfer surface 14 that will ultimately function as the ITM, thereby leaving imperfections in the doctor blade unaffected to the quality of the finished product. After curing, the "release" layer 16 may have a thickness of between about 2 microns and about 200 microns. The apparatus in which such steps and methods may be implemented is schematically illustrated in fig. 24A and 24B.
For example, the release layer formulation detailed above may be uniformly applied to a PET carrier, leveled to a thickness of 5-200 micrometers (μ), and cured at 120-130 ℃ for about 2-10 minutes. Surprisingly, the hydrophobicity of the ink transfer surface of the release layer so prepared, as assessed by its Receding Contact Angle (RCA) of 0.5-5 microliter (μl) of distilled water droplets, can be about 60 °, while the other side of the same release layer, which is used to approximate the hydrophobicity of a layer typically prepared with an air interface, can have a substantially higher RCA, typically about 90 °. The PET carrier used to create the ink transfer surface 14 may typically exhibit an RCA of about 40 ° or less. All contact angle measurements were performed with contact angle analyzers-krussTM "Easy Drop" FM40Mk2 and/or DATAPHYSICS OCA Pro (PARTICLE AND Surface Sciences pty.ltd., gosford, NSW, australia).
In a subsequent step of the method, the result is shown in fig. 18, where a further layer 18 (referred to as a compliant layer) is applied to layer 16 on the side opposite the ink transfer surface 14. Compliant layer 18 is an elastomeric layer that allows layer 16 and its outermost surface 14 to closely follow the surface contour of the substrate upon which the ink image is imprinted. Attaching compliant layer 18 to the side opposite ink transfer surface 14 may include applying an adhesive or bonding composition in addition to the material of compliant layer 18. In general, compliant layer 18 will typically have a thickness of between about 100 microns and about 300 microns or greater.
While compliant layer 18 may have the same composition as release layer 16, material and process economics may warrant the use of less expensive materials. Further, the compliant layer 18 is typically selected to have different mechanical properties (e.g., greater stretch resistance) than the release layer 16. Such desired property differences may be achieved, for example, by utilizing different compositions relative to the release layer 16, by varying the ratio between the ingredients of the formulation used to prepare the release layer 16, and/or by adding additional ingredients to such formulation, and/or by selecting different curing conditions. For example, the addition of filler particles may advantageously increase the mechanical strength of compliant layer 18 relative to release layer 16.
In some embodiments, compliant layer 18 may comprise various rubbers. Preferably, such rubbers are stable at temperatures of at least 100 ℃ and may include rubbers such as alkyl acrylate copolymer rubber (ACM), methyl vinyl silicone rubber (VMQ), ethylene propylene diene monomer rubber (EPDM), fluoroelastomer polymers, nitrile rubber (NBR), ethylene acrylic Elastomer (EAM), and hydrogenated nitrile rubber (HNBR).
As a non-limiting example, one willLSR 2530 (Momentive Performance Materials inc., waterford NY.) two-component liquid silicone rubber was applied to the previously described cured release layer 16, with the two components mixed in a 1:1 ratio. The silicone rubber mixture was metered/leveled with a doctor blade to obtain an initial compliant layer 18 having a thickness of about 250 microns, and then cured at 150-160 ℃ for about 5 minutes.
In a subsequent step of the method, the result is shown in FIG. 19, where a reinforcing or support layer 20 is constructed on compliant layer 18. The support layer 20 typically comprises a fibrous reinforcing material in the form of a web or fabric to provide the support layer 20 with sufficient structural integrity to withstand stretching while the ITM remains taut in the printing system. The support layer 20 is formed by coating a fiber-reinforced material with a resin that is subsequently cured and retains flexibility after curing.
Alternatively, the support layer 20 may be formed separately as a reinforcing layer, including such fibers embedded and/or impregnated within a separately cured resin. In such a case, support layer 20 may be attached to compliant layer 18 via an adhesive layer, optionally eliminating the need to cure support layer 20 in situ. In general, support layer 20, whether formed in situ on compliant layer 18 or separately, may have a thickness of between about 100 microns and about 500 microns, a portion of which is due to the thickness of the fibers or fabric, which typically varies between about 50 microns and about 300 microns. However, the support layer thickness is not limiting. For heavy duty applications, for example, the support layer may have a thickness greater than 200 microns, greater than 500 microns, or 1mm or greater.
For example, to the multi-layer ITM structure described herein, including the vinyl-functionalized release coating 16 and the bi-component silicone rubber compliant layer 18, a support layer 20 comprising a woven fabric of glass fibers is applied. The fiberglass fabric having a thickness of about 100 microns is a plain weave fabric having 16 yarns/cm in the vertical direction. Embedding a glass fiber fabric into a liquid silicone rubber comprising a layer corresponding to the compliant layerLSR 2530 in a curable fluid. In summary, the resulting support layer 20 has a thickness of about 200 microns and cures at 150 ℃ for about 2-5 minutes. Preferably, a denser woven fabric (e.g., having 24x23 yarns/cm) may be used.
After the support layer 20 is formed or attached in situ, additional layers may be constructed on its back side as desired. Fig. 20 shows an optional carpet 22 secured to the opposite side of the support layer 20 (e.g., by a cured adhesive or resin), and fig. 21 shows a high friction layer 24 applied to the opposite side of the carpet 22. As will be appreciated by those skilled in the art, a variety of relatively soft rubbers may be used to prepare layers having high friction properties, silicone elastomers being but one example of such rubbers. The high friction layer 24 may be directly attached to the support layer 20 without the presence of an intervening layer such as blanket 22.
As described above, all layers (e.g., 18, 20, 22, 24 or any intervening adhesive or primer layers, etc.) of the peel-off layer added to the ITM collectively form the base of the structure, as shown with respect to the base 200 in fig. 23C.
Prior to use of the ITM, the carrier 10 must be removed to expose the ink transfer surface 14 of the release layer 16, as shown in fig. 22. In general, the finished product can be simply peeled off the carrier 10.
If the carrier 10 is a flexible foil, it may preferably be left in place on the ITM until the ITM is installed in the printing system. The foil will serve to protect the ink transfer surface 14 of the ITM during storage, transport and installation. In addition, after the manufacturing process is completed, the carrier 10 may be replaced by a substitute foil suitable as a protective film.
Fig. 24A-24D schematically illustrate an apparatus 90 that can manufacture ITM. Fig. 24A provides a schematic illustration of such an apparatus 90, the apparatus 90 having an unwind roller 40 and a wind-up roller 42 that move a flexible endless conveyor 100. A dispensing station 52 may be positioned along the path followed by the conveyor 100 capable of dispensing a curable fluid composition suitable for the desired ITM, a leveling station 54 capable of controlling the thickness of the curable layer as it moves downstream of the station, and a curing station 56 capable of at least partially curing the layer so that it can be used as an initial layer for subsequent steps, if any. Dispensing station 52, leveling station 54, and curing station 56 comprise layer forming station 50a. As shown at 50b, apparatus 90 may optionally include more than one layer forming station. In addition, the forming station 50 may include additional sub-stations, shown by dispensing roller 58 in station 50a.
In some embodiments, the need for an endless conveyor 100 is avoided, with the carrier 10 being directly tensioned between rollers 40 and 42. The raw carrier 10 is unwound from an unwind roll 40 and, after passing through stations 50a and 50b, rewound onto a wind-up roll 42.
Although not shown in the figures, the apparatus may also include a "surface treatment" station upstream of the dispensing station that facilitates the subsequent application of the curable composition or, depending on the particular case, its attachment to the carrier contact surface or initial layer. As described with respect to the carrier, an optional surface treatment station (not shown) may be adapted for physical treatment (e.g., corona treatment, plasma treatment, ozonation, etc.).
Fig. 24B schematically shows how a carrier 10 placed on a conveyor 100 is coated in a forming station 50 of an apparatus 90. At the dispensing station 52, the curable composition 36 of the release layer 16 is applied to the carrier contact surface 12. As the carrier 10 is driven in the direction of the arrow, the curable composition 36 is leveled to a desired thickness at the leveling station 54, for example, by using a doctor blade. As the smoothening layer proceeds downstream, it enters a curing station 56, which curing station 56 is configured to at least partially cure the curable composition 36, thereby enabling the formation of the initial layer 16 on the exit side of the curing station. Such exemplary steps have been described in connection with fig. 16 and 17.
Fig. 24C and 24D schematically show how additional layers are applied (forming the base). In fig. 24C, curable composition 38 is dispensed at a dispensing station 52 (which may be the same as or different from the station used to coat the carrier with release layer 16, as shown in fig. 24B). Curable composition 38 is flattened to a desired thickness at flattening station 54, then enters curing station 56, and exits curing station 56 with sufficient cure to serve as initial layer 18 for subsequent steps, etc. Such exemplary steps have been described in connection with fig. 18. Referring now to fig. 24C, fig. 24C schematically depicts the curable composition 39 applied at the dispensing station 52. The body of the support layer (e.g., fabric) may be conveyed by a dispensing roll 58. The exemplary fabric may be immersed in the curable composition at station 60 before it enters curing station 56. In this way, the support layer 20 may be formed on the outlet side of the curing station.
Fig. 23A and 23B schematically illustrate how defects occur in portions of an outer layer 80 (e.g., a release layer) prepared according to the above-described methods of the art. Fig. 23A illustrates a different phenomenon associated with bubbles that may be trapped in any curable composition if curing occurs before such bubbles can be eliminated (e.g., by degassing). As can be seen from the figure, as the microbubbles 82 migrate toward the air interface, the layer 80 is oriented on the body 800 during fabrication, so they can merge into larger bubbles along the direction of migration (indicated by the arrows). The bubbles (regardless of their size) may remain trapped within or on the surface of the body of the layer, with the upper portion of the bubble envelope forming the protrusion 84. When bubbles adjacent to the surface collapse while the layer solidification proceeds, the pits 86 can remain even if the cladding portion of the bubbles protruding from the surface disappears. Thus, these phenomena generally provide a "gradient" of bubbles, with the upper portion generally being filled with larger bubbles and/or having a higher bubble density per cross-sectional area or volume than the lower portion, lower and higher relative to orientation during layer fabrication. The effect of bubble-derived defects on the surface is self-evident, as surface heterogeneity typically has a negative impact on any subsequent interaction with, for example, an ink image. Over time, such ITMs typically operate under tension and/or under pressure, and the pits may widen and merge to form more pronounced cracks. Thus, this phenomenon may affect the structural integrity of the surface, and any mechanical properties such as integrity will be imparted to the ITM.
Fig. 23B schematically illustrates a different phenomenon associated with solid contaminants such as dust. Although dust is shown in addition to bubbles in the present illustration, this need not necessarily be the case, and each such surface or layer defect can occur independently. As can be seen from the figure, solid contaminants may remain on the surface. If settling of contaminants occurs after the outer layer 80 has cured, these contaminants 92 may even be removed by properly cleaning the outer surface. Still, this phenomenon is undesirable because it requires additional processing before such ITM can be used. If such contamination occurs while the layer is still uncured, the contaminants may be trapped on the surface of layer 80 (e.g., contaminant 94, which appears to be "floating") or may even be submerged within the lift-off layer (e.g., contaminant 96). As can be readily appreciated, larger/heavier contaminants can sink deeper than smaller/heavier contaminants.
Unlike methods known in the art, the methods disclosed herein include forming a layer of fluid first curable material, wherein one side of the layer contacts a carrier contact surface, the layer constituting an initial release layer. The carrier contact surface serves to protect the initial release layer, imparting the desired properties to the ink transfer layer, while the carrier serves as a physically strong support structure upon which other layers are added to form the ITM until the ITM is completed. As a result, many potential sources of defects are avoided. Furthermore, the finish of the ink transfer surface is primarily, if not exclusively, determined by the carrier contact surface.
Fig. 23C schematically illustrates a cross-section through an outer layer 16 (e.g., a release layer) prepared according to the method of the present invention. For comparison with previous figures execution, a cross section is shown without carrier and with the same orientation as in fig. 23A and 23B, although fabrication is performed in the inverted orientation as indicated by the arrow. As will be described in detail below, the base 200 is attached to the first outer layer 16 after the layers are at least partially cured, and is therefore not equivalent to the body 800 having been used as a support during the manufacturing process. For illustrative purposes only, layer 16 is shown to include a significant number of bubbles 82, but this is not necessarily the case. However, if present, such bubbles will exhibit a different pattern than previously described. First, since the now uppermost ink transfer surface 14 of layer 16 is in advance in contact with the carrier, no protrusions are observed, and thus the release layer is free of phenomena such as those previously shown by surface protruding bubbles 84. Also, the pits previously shown as cavities 86 are highly unlikely because they mean that incompatible curable layers and carriers are used. According to the method of the present invention, the curable material suitably wets the carrier as a result of the formation of the outer layer, and it is believed that substantially no bubbles are entrained between the carrier and the initial layer formed thereon. Thus, such bubbles, if present, will be disposed in the bulk of the layer. However, since the fabrication is performed in an inverted orientation as compared to the conventional method, the gradient of the bubbles will be inverted for the same reason. Thus, and as depicted in fig. 23C, the micro bubbles are closer to the outer surface than the macro bubbles, which are closer to the base.
The inventive release layer structures prepared from addition-cured formulations may be substantially free of functional groups, or non-substantial amounts of functional groups (e.g., non-substantial amounts of OH groups), covalently attached within a polymer matrix. For example, these functional groups may include moieties such as c= O, S =o and OH.
Because these release layer structures contain at most an insignificant amount of such functional groups, it is expected that the release layer will be highly hydrophobic. However, the inventors have surprisingly found that the surface of the release layer produced by the method of the invention may in fact be slightly hydrophilic and significantly more hydrophilic than the corresponding release layer, i.e. the release layer has the same composition but is manufactured using conventional curing techniques, wherein the release layer is exposed to air ("standard air curing"). Without wishing to be bound by theory, the inventors believe that the intimate contact between the carrier contact surface and the initial release layer surface induces a slightly hydrophilic nature of the carrier contact surface in the release layer surface.
As discussed above, ITM release layers with low surface energy can facilitate transfer of dried ink images to a print substrate. However, during the ink receiving phase, aqueous ink droplets ejected onto such low energy hydrophobic release layers tend to bead up after initial impact, thereby compromising image quality. A higher energy, less hydrophobic release layer can mitigate this effect, but is detrimental to image transfer quality. The inventors have found that the release layer structures of the present invention generally have a release surface characterized by a moderately hydrophobic character, as indicated by a receding contact angle of distilled water of at most 80 °, or at most 70 °, typically at most 60 °, or at most 50 °, and more typically 30 ° -60 °, 35 ° -60 °,30 ° -55 °,30 ° -50 °,30 ° -45 °, or 35 ° -50 °. However, surprisingly, both ink receiving and transfer of the dry heated ink image can be of good quality. It has to be emphasized that by using a carrier surface with a higher hydrophilicity (lower contact angle with respect to distilled water drops) and/or by corona (or similar) treatment, lower receding contact angle values (and dynamic contact angles discussed below) can be achieved.
Without wishing to be bound by theory, the inventors believe that the above-described induced surface properties improve the interaction between polar groups (e.g., O-Si-O) on the release layer surface and corresponding polar moieties (e.g., OH groups in water) in the aqueous liquid (e.g., aqueous inkjet ink) deposited thereon, thereby helping to receive the ejected ink droplets. Subsequently, after drying the ink and heating the ink film to transfer temperature, these interactions are attenuated, enabling the dried or substantially dried ink image to be completely transferred. Thus, the performance of the present release layer structure, both in the ink receiving stage and in the ink film transfer stage, is significantly better than that expected for release layers having moderately hydrophobic properties but without the special surface structure and properties induced by the carrier contact surface.
Examples
Reference is now made to the following examples, which together with the above description illustrate the invention in a non-limiting manner.
Bill of materials used:
The support used as a substrate in the production of the release layer surface includes (1) antistatic polyester films (examples 1-7), (2) untreated polyester films, i.e., non-antistatic (example 11), and (3) aluminized polyester films (example 10).
Example 1
The ITM release layer of example 1 had the following composition (by weight):
a release layer is prepared substantially as described in the blanket preparation procedure of the present invention, as follows.
Blanket preparation procedure (Release layer for curing on support surface)
All components of the peel ply formulation were thoroughly mixed together. An initial release layer of the desired thickness was coated onto a PET sheet using a rod/knife (other coating methods may also be used) and then cured at 150 ℃ for 3 minutes. Subsequently, a knife was used to coat the Siloprene LSR 2530 on top of the release layer to obtain the desired thickness. Curing was then performed at 150 ℃ for 3 minutes. Another layer of Siloprene LSR 2530 is then coated on top of the previous (cured) silicone layer and the fiberglass fabric is incorporated into this wet fresh layer, thereby allowing the wet silicone to penetrate into the fabric structure. Curing was then performed at 150 ℃ for 3 minutes. The last layer of Siloprene LSR 2530 was then coated onto a fiberglass fabric and cured again at 150 ℃ for 3 minutes. The whole blanket construction was then cooled to room temperature and PET was removed.
Example 2
The ITM release layer of example 2 had the following composition:
The blanket was prepared essentially as described in example 1.
Example 3
The ITM release layer of example 3 had the following composition:
| Component name | Parts by weight |
| DMS-V35 | 70 |
| XPRV-5000 | 30 |
| VQM-146 | 40 |
| Inhibitor 600 | 5 |
| SIP6831.2 | 0.1 |
| Crosslinking agent 100 | 6.5 |
| Silsurf A010-D-UP | 5 |
The blanket was prepared essentially as described in example 1.
Example 4
The ITM release layer of example 4 had the following composition:
| Component name | Parts by weight |
| DMS-V35 | 100 |
| VQM-146 | 40 |
| Inhibitor 600 | 3 |
| SIP6831.2 | 0.1 |
| Crosslinking agent HMS-301 | 5 |
The blanket was prepared essentially as described in example 1.
Example 5
The ITM release layer of example 5 was composed ofLSR 2530 (Momentive Performance Materials inc., waters, NY) two-component liquid silicone rubber was prepared, wherein the two components were mixed in a 1:1 ratio. The blanket was prepared essentially as described in example 1.
Example 6
The ITM release layer of example 6 had substantially the same composition as example 4, but contained a commercially available silicone-based resin SR545 (Momentive Performance Materials inc., waterford, NY) containing polar groups. These polar groups are of the "MQ" type, where "M" stands for Me3 SiO and "Q" stands for SiO4. The complete composition is as follows:
| Component name | Parts by weight |
| DMS-V35 | 100 |
| VQM-146 | 40 |
| SR545 | 5 |
| Inhibitor 600 | 3 |
| SIP6831.2 | 0.1 |
| Crosslinking agent HMS-301 | 5 |
The blanket was prepared essentially as described in example 1.
Example 7
The ITM release layer of example 7 had substantially the same composition as example 6, but included polymer RV 5000, which included a vinyl-functional polydimethylsiloxane having a high density of vinyl groups, as described above. The complete composition is as follows:
| Component name | Parts by weight |
| DMS-V35 | 70 |
| RV 5000 | 30 |
| VQM-146 | 40 |
| Inhibitor 600 | 5 |
| SIP6831.2 | 0.1 |
| Crosslinking agent HMS-301 | 12 |
| SR545 | 5 |
The blanket was prepared essentially as described in example 1.
Comparative examples 1A to 1F
The ITM release layers were prepared as "corresponding release layers" or "reference release layers" of the compositions of examples 1-6, such that the corresponding release layers (referred to as comparative examples 1A-1F) had the same compositions as examples 1-6, respectively. However, during the curing of the release layer, the release layer surface (or "ink receiving surface") is exposed to air ("standard air curing") according to conventional manufacturing procedures provided below.
Comparative blanket preparation procedure (release layer was exposed to air during curing)
The first layer of Siloprene LSR 2530 was coated on PET sheet using a bar/knife and then cured at 150 ℃ for 3 minutes to obtain the desired thickness. Another layer of Siloprene LSR 2530 is then coated on top of the previous (cured) silicone layer and a fiberglass fabric is incorporated into this wet fresh layer, thereby allowing the wet silicone to penetrate into the fabric structure. Siloprene LSR 2530 was then coated on top of the fiberglass fabric and cured at 150℃for 3 minutes. All components of the peel ply formulation were thoroughly mixed together prior to formation of the initial peel ply. The release layer was coated on top of cured Siloprene LSR 2530 to obtain the desired thickness, then cured at 150 ℃ for 3 minutes while exposing the release layer surface to air.
Example 8
The procedure used to perform the Receding Contact Angle (RCA) and Advancing Contact Angle (ACA) measurements using a dedicated DATAPHYSICS OCA Pro contact angle measurement device (PARTICLE AND Surface Sciences pty) is dr. Roger p. Woodward (a conventional technique set forth in detail in particular "Contact Angle Measurements Using the Drop Shape Method", www.firsttenangstroms.com/pdfdocs/CAPaper.pdf)).
The results of examples 1-6, as well as the results of the release layers produced according to comparative examples 1A-1F, are provided below.
In almost all cases, the release surface generated against the support surface exhibits a lower receding contact angle than the same formulation cured in air. More typically, the resulting release surface relative to the carrier surface exhibits a receding contact angle of at least 5 °, at least 7 °, at least 10 °, at least 12 °, or at least 15 °, or 5 ° -30 °,7 ° -30 °,10 ° -30 °,5 ° -25 °,5 ° -22 °,7 ° -25 °, or 10 ° -25 °.
Example 9
The release surfaces produced in examples 1-6 and the corresponding release surfaces produced in comparative examples 1A-1F were aged at 160 ℃ for 2 hours to simulate aging of the release layer under extended operating conditions. The receding contact angle was measured and the results were as follows:
With respect to the comparative example, it is apparent that the retreating contact angle is substantially maintained after the aging process is performed. However, with respect to examples 1-6 of the present invention, it is apparent that the receding contact angle is typically increased by 4 ° -15 ° after the aging process is performed. Without wishing to be bound by theory, the inventors believe that the increase in contact angle in the release layer structure of the present invention may be due to a loss of hydrophilic behavior (or an increase in hydrophobic behavior) due to some change in the position of the polar groups (e.g., si-O-Si) on the release layer surface.
Example 10
A blanket comprising a release layer of the composition of example 2 was prepared substantially as described in example 1, but for an aluminized PET carrier surface.
Example 11
A release layer having the release layer composition of example 2 was prepared substantially as described in example 1, but for a commercially available PET carrier surface that was not subjected to antistatic pretreatment.
Example 12
The release layers produced in examples 2, 10 and 11 according to the present invention were subjected to contact angle measurements to determine both advancing and receding contact angles. The results were as follows:
Examples 10 and 11 exhibited receding contact angles that were about 30 ° less than the receding contact angles of the same compositions where the release layer was cured when exposed to air. The release layer surface of example 2 prepared for the antistatic PET carrier surface exhibited a receding contact angle that was about 50 ° less than the receding contact angle of the same composition prepared upon exposure to air.
Example 13
The support surfaces utilized in examples 2, 10 and 11 were subjected to contact angle measurements to determine both advancing and receding contact angles. The results were as follows:
From the receding contact angles obtained, it can be seen that the three support surfaces exhibited hydrophilic behaviour and that PET subjected to antistatic treatment exhibited the most hydrophilic behaviour (20 ° RCA versus 40 ° RCA).
Notably, the hydrophilic behaviour of the support surface is at least partially induced in the respective release surfaces by the cured formulation having an RCA of 65 ° upon exposure to air, by the same formulation prepared for the antistatic PET surface having an RCA of 45 °, by the antistatic PET support used exhibiting an RCA of 20 °. Thus, the release layer structure of the present invention has a release surface with hydrophilic/hydrophobic properties intermediate between those of the same formulation cured in air and the carrier surface itself.
Example 14
The release layer surface energy of the ink receiving surface of example 1A cured upon exposure to air, example 1 cured for an antistatic PET surface, and example 1 cured for an antistatic PET surface and then subjected to a standard aging procedure for 2 hours at 160 ℃ was calculated. These three examples have the same chemistry.
For each of these examples, the total surface energy was calculated using a classical "harmonic mean" method (also known as the Owens-Wendt surface energy model, see, e.g., KRUSS Technical Note TN306 e). The results were as follows:
| Release agent | Total surface energy J/m2 |
| EXAMPLE 1A air curing | 20.9 |
| EXAMPLE 1 aging | 22.6 |
| Example 1 | 26.1 |
In example 1A, the release layer surface was extremely hydrophobic upon curing upon exposure to air, and as expected the total surface energy of the surface was low, 20.9J/m2. For Polydimethylsiloxane (PDMS), this is very close to the literature values for surface energy. Notably, example 1, which was surface cured for antistatic PET, exhibited a total surface energy of about 26J/m2, which was moderately less hydrophobic than the "air-cured" sample. The total surface energy after the formulation is subjected to standard aging procedures is reduced from about 26J/m2 to below 23J/m2. This result appears to confirm the RCA results obtained for the various aged and unaged materials of this exemplary formulation.
Example 15
The release layer surface energy of the ink receiving surface of example 2A cured upon exposure to air, example 2 for antistatic PET surface cure, and example 2 for antistatic PET surface cure, followed by a standard aging procedure at 160 ℃ for 2 hours, was calculated. These three examples have the same chemistry.
As in example 14, the total surface energy was calculated using a classical "harmonic mean" method. The results were as follows:
| Release agent | Total surface energy (J/m2) |
| EXAMPLE 2A air curing | 34.6 |
| EXAMPLE 2 aging | 39.9 |
| Example 2 | 49.1 |
In example 2A, the release layer surface was less hydrophobic than the release layer of example 1A when cured upon exposure to air, the total surface energy of the surface being about 35J/m2. Notably, example 2 for antistatic PET surface cure exhibited a total surface energy of about 49J/m2, which had significantly lower hydrophobicity than the "air cured" sample. After such formulations are subjected to standard aging procedures, the total surface energy is reduced from about 49J/m2 to about 40J/m2. This result appears to confirm the RCA results obtained for the various aged and unaged materials of this exemplary formulation.
Example 16
The temperature of the blanket surface is maintained at 75 ℃. The image (typically a 10-100% color gradient) is printed on the blanket at a speed of 1.7 meters per second with a resolution of 1200dpi. An uncoated paper (A4 Xerox Premium Copier Paper,80 gsm) was placed between the press roll and the blanket and the roll was pressed against the blanket while the pressure was set to 3 bar. The rollers move over the sheet, exerting pressure on the line of contact between the blanket and the sheet and facilitating the transfer process. In some cases, incomplete transfer may be observed, with ink residue remaining on the blanket surface. To evaluate the extent of ink residue, a glossy paper (A4 Burgo glossy paper 130 gsm) was applied over the blanket, similar to the uncoated paper, and the transfer process was performed again. Any ink that remains on the blanket and that is not transferred to the uncoated paper will be transferred to the glossy paper. Thus, the ink residue (in% of image surface area) of the glossy paper can be evaluated according to the following ratio:
a-no visible residues
B-1-5% of visible residue
C-visible residue of more than 5%
The results of the evaluation are as follows:
| Release agent | Transfer grade |
| Example 4 | B |
| Example 1 | B |
| Example 2 | A |
| Example 3 | A |
| Example 6 | C |
Example 17
Example 16 was repeated for the release surfaces of examples 2 and 3, but with a printing speed on the blanket of 3.4 m/s. Both release surfaces maintained a transfer rating of a.
Example 18
The ITM release layer compositions of examples 2 and 3 were cured relative to the PET substrate according to the procedure provided in example 1. The ITM release layer compositions of examples 2 and 3 were cured relative to air according to the procedure provided in comparative examples 1B and 1C. The samples were then subjected to Dynamic Contact Angle (DCA) measurements at 10 seconds and then at 70 seconds according to the following procedure:
the droplets are placed on a smooth PTFE film surface so that the droplets fall as little as possible, and thus the kinetic energy does not spread the droplets. Then forming hanging droplets. Subsequently, the sample is raised until it touches the bottom of the drop. If the drop is large enough, the adhesion of the surface will pull it off the needle tip. The needle tip is positioned above the surface at a height such that a growing pendant drop will contact the surface and break off before it falls freely due to its own weight.
The dynamic contact angles were then measured at 10 seconds and 70 seconds. The results were as follows:
It was observed that the initial measurement of the dynamic contact angle at 10 seconds provided a strong indication of the hydrophilicity of the release layer surface. Subsequent measurements at 70 seconds provide an indication of the extent to which any liquid (e.g., polyether glycol functionalized polydimethylsiloxane) disposed within the release layer has been incorporated into the droplets. This binding may further reduce the measured DCA.
Thus, samples cured for PET exhibited significantly lower (more hydrophilic) initial DCA measurements (105 °, 87 °) relative to the hydrophilic initial DCA measurements (114 °, 113 °) for corresponding samples cured for air. In addition to the hydrophilicity shown, samples cured for PET showed 8 ° to 17 ° DCA drop between the first and second measurements.
Figures 25A-25C provide images of various ink patterns printed onto a release layer of an ITM of the present invention, wherein the release layer of example 2 is cured against a PET carrier surface. Fig. 26A-26C are images of the same ink pattern printed onto the release layer of example 2, but wherein the release layer was cured for air. Comparing fig. 25A and 26A, it is apparent that the release layer of the ITM of the present invention exhibits higher optical density and more accurately reflects the ink image pattern. The comparison between fig. 25C and 26C yields the same conclusion. A comparison is now made between fig. 25B and 26B, it being apparent that each dot in fig. 25B is significantly larger than the corresponding dot in fig. 26B.
As used in this specification and in the claims section that follows, the term "receding contact angle" or "RCA" refers to the receding contact angle measured at ambient temperature using the DATAPHYSICS OCA Pro contact angle measurement device or comparable video-based optical contact angle measurement system using the drop shape method described above. Similar "advancing contact angle" or "ACA" refers to an advancing contact angle measured in substantially the same manner.
As used in this specification and the claims that follow, the term "dynamic contact angle" or "DCA" refers to a dynamic contact angle as measured at ambient temperature using the method detailed in "Contact Angle Measurements Using the Drop Shape Method" above using the DATAPHYSICS OCA Pro contact angle measurement device or comparable video-based optical contact angle measurement system, using Roger p.woodward doctor, and as detailed in example 17 above.
As used in this specification and the claims that follow, the term "standard aging procedure" refers to a accelerated aging regimen performed in a standard convection oven at 160 ℃ for 2 hours for each peel ply tested.
As used in this specification and the claims that follow, the term "standard air cure" refers to a conventional curing process for curing a release layer, as described with respect to comparative examples 1A-1F, wherein the release layer surface (or "ink receiving surface") is exposed to air during curing of the release layer.
As used in this specification and in the claims section that follows, the term "bulk hydrophobicity" is characterized by the receding contact angle of a distilled water droplet disposed on the inner surface of the lift-off layer that is formed by exposing regions of cured silicone material within the lift-off layer.
With respect to examples C1-C12, the viscosity of each sample measured at room temperature is provided below (all values are in cP):
C1=19.2
C2=18.15
C3=22.3
C4=36.2
C5=19.8
C6=21.2
C7=28.1
C8=18.0
C9=50.0
C10=48.2
C11=20.2
C12=20.7
For these 12 exemplary formulations, the surface tension of these aqueous treatment formulations is more uniform and is typically in the range of 26 to 29mN/m, or 26 to 28mN/m, at room temperature.
Examples C1 to C12
Exemplary compositions of the ITM aqueous treatment fluids of the present invention are provided in the following table:
Examples C13 to C22
The composition of the ITM aqueous treatment fluids and their various properties are provided in the table below as example compositions C13 to C22.
Example C23
Additional aqueous treatment formulations are provided in example C23. This formulation is free of surfactants except for quaternary ammonium salts (Larostate 264A) which are present in relatively high percentages (8 wt%) to substantially reduce the surface tension of the aqueous treatment formulation. The surface tension and viscosity at room temperature were 32.3mN/m and 17.8cP, respectively.
Preparation of pigments
The pigments used in the examples described below are generally supplied in an initial particle size of a few microns. These pigments are milled to the submicron range in the presence of a dispersant, and the two materials are fed as an aqueous mixture to a milling apparatus. Unless otherwise indicated, 30g of pigment was mixed with a dispersant of a weight satisfying the weight ratio shown in the following examples. Deionized water was added to a balance of 200 g. In Union Process Attritor HDDM-01/HD-01, the liquid slurry is reduced in size in the presence of 4500g of 0.8mm diameter chrome steel beads (GLEN MILLS Inc., USA) and at an energy input for a period of time sufficient to produce a mill-base comprising pigment particles having a median diameter (as analyzed by particles per volume) of 100nm or less (DV50cm. Ltoreq.100 nm). Typically, the mill is operated at about 3000rpm for at least 48 hours, the duration of milling also being dependent on the initial particle size.
The particle size and distribution in the composition so prepared were determined using the DLS method (Malvern Zetasizer Nano ZS). Unless otherwise indicated, aliquots were removed from the contemplated compositions and, if desired, diluted in Double Distilled Water (DDW) to obtain samples with a solids concentration of about 1 wt.%. Prior to DLS measurement, the liquid samples were briefly sonicated (about 7 seconds at 75% of maximum power in Sonics Vibracell VCX 750,750 watts) to ensure proper dispersion of pigment particles during evaluation of particle size and distribution. Based on the results of the volumetric analysis of the particles.
Once the pigment-dispersant mixture reached the desired particle size, 50g of water was added to the chamber of the milling apparatus and the resulting diluted dispersion was extracted therefrom. The beads are separated by filtering the diluted mill-base through a suitable screen. The pigment concentration at this stage was 12% by weight.
To the mill base containing the pigment dispersant, sodium laurate (SDD) and/or at least one additive from the group consisting of potassium laurate, sodium oleate, potassium oleate, sodium myristate, potassium myristate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, potassium octoate and sodium octoate are added. Water was added as needed to produce a composition having a pigment concentration of 10% by weight.
Example I1-ink composition
In this example, the preparation of an ink composition will be describedBlue D7079 is combined in HDDM-01/HD-01 grinding mill as described above190 Are ground together, the materials are mixed in the following proportions:
the milling concentrate, now having a DV50 of less than 100nm, was further diluted with 50g of water and extracted from the milling apparatus at a pigment concentration of 12% by weight. The millbase concentrate is further processed as described below to prepare an ink composition.
In the first stage, 2.4g of sodium laurate was added to 200g of millbase concentrate, resulting in a millbase. The mixture was stirred to homogeneity (5' magnetic stirrer, 50 rpm) and incubated at 60 ℃ for 1 day. The mixture was then cooled to ambient temperature.
In the second stage, the ink ingredients were added to the mill base as follows:
the mixture was stirred at ambient temperature for 30 minutes to give an ink jettable ink composition having a viscosity of less than 10 cP.
Examples I2 to I5 ink compositions
The ink of example I1 was formulated, but 5g, 10g, 12g and 15g TWEEN 20 were added, respectively.
Point gain
The dot gain is the increase in pointing size relative to the initial spherical drop diameter. The dot gain is determined by the ratio of the final dot diameter to the initial droplet diameter. It is highly desirable to find a way to increase the dot size without having to increase the drop volume.
Using the inventive techniques disclosed herein, the inventors achieved a point gain of at least 1.5 or 1.6, and more typically at least 1.7, at least 1.8, at least 1.9, or at least 2.0, or in the range of 1.5 to 2.2, 1.5 to 2.1, 1.7 to 2.1, or 1.8 to 2.1.
For example, using droplets with a volume of 6.3 picoliters (d=22.9 microns) and using the aqueous treatment formulation of the present invention, dry ink dots were obtained in the diameter range of 40 microns to 48 microns.
As used herein in this specification and in the claims section that follows, the terms "hydrophobic" and "hydrophilic" and the like may be used in a relative sense, and are not necessarily in an absolute sense.
As used herein in this specification and in the claims section that follows, the term "functional group" refers to a group or moiety that is attached to the polymer structure of the release layer and has a higher polarity than the O-Si-O groups of conventional addition cured silicones. Various embodiments are provided herein. The inventors have observed that the neat addition cured polydimethylsiloxane polymers contain both O-Si-O, siO4、Si-CH3 and C-C groups and that most other functional groups will have a higher dipole, thus making them considered "functional". Those skilled in the art will appreciate that these functional groups may have a tendency or strong tendency to react with components typically present in aqueous inks utilized in indirect inkjet printing at processing temperatures up to 120 ℃.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the event of a conflict, the present specification, including definitions, will control.
In the description and claims of the present disclosure, each of the verbs "comprise," "include," and "have" and their conjugates is used to indicate that the subject or subjects of the verb are not necessarily a complete list of members, components, elements, steps, or parts of the subject or subjects of the animal word. These terms encompass the term "consisting of; the sum is basically composed of a. Composition.
Thus, as used herein, the singular forms "a," "an," and "the" include plural references and mean "at least one" or "one or more" unless the context clearly dictates otherwise.
Positional or operational terms such as "upper," "lower," "right," "left," "bottom," "below," "low," "top," "above," "elevated," "high," "vertical," "horizontal," "rearward," "forward," "upstream" and "downstream," and grammatical variations thereof, may be used herein for exemplary purposes only to describe the relative positioning, location, or displacement of certain components to indicate either the first component and the second component, or both, in the current drawing. These terms do not necessarily indicate that, for example, a "bottom" component is below a "top" component, and that the component or components, or both, may be flipped, rotated, moved, placed in a diagonal orientation or position, placed horizontally or vertically, or similarly modified in space in such an orientation.
Unless otherwise indicated, the use of the expression "and/or" between the last two members of the list of options for selection indicates that it is appropriate and possible to select one or more of the listed options.
As used herein in the specification and in the claims section that follows, the term "%" refers to weight percent unless explicitly specified otherwise.
Similarly, the term "ratio" as used in this specification and the preceding claims section refers to weight ratios unless explicitly specified otherwise.
In this disclosure, adjectives such as "substantially" and "about" modifying a condition or a relational feature of one or more features of an embodiment of the present technology are understood to mean that the condition or feature is defined within a tolerance range acceptable for operation of the embodiment of the intended application, unless otherwise specified.
While the present disclosure has been described in terms of certain embodiments and generally associated methods, alterations and permutations of the embodiments and methods will be apparent to those skilled in the art. The present disclosure should be understood not as limited by the specific embodiments described herein, but only by the scope of the appended claims.